diff --git a/src/Compiler/CoreInitializationPass.php b/src/Compiler/CoreInitializationPass.php
index da785a47..92b4bd81 100644
--- a/src/Compiler/CoreInitializationPass.php
+++ b/src/Compiler/CoreInitializationPass.php
@@ -63,7 +63,7 @@ public function process(ContainerBuilder $container)
             $container->setParameter('paths.modules.'.$module->getShortName(), $module->getPath());
             $composerName = $module->getComposerName();
             if ($composerName) {
-                list($vendor,$name) = explode('/', $composerName);
+                list($vendor,$name) = explode('/', $composerName ?? '');
                 $container->setParameter('paths.modules.'.$vendor.'.'.$name, $module->getPath());
             }
         }
diff --git a/src/Context/BasicContext.php b/src/Context/BasicContext.php
index 468af3f4..dab5810a 100644
--- a/src/Context/BasicContext.php
+++ b/src/Context/BasicContext.php
@@ -97,7 +97,7 @@ private function getSubclassesOf($parent): array
     {
         $result = [];
         foreach (get_declared_classes() as $class) {
-            if (is_subclass_of($class, $parent)) {
+            if (is_subclass_of($class, $parent ?? '')) {
                 $result[] = $class;
             }
         }
@@ -211,9 +211,9 @@ public function handleAjaxBeforeStep(BeforeStepScope $event)
         }
         try {
             $ajaxEnabledSteps = $this->getMainContext()->getAjaxSteps();
-            $ajaxEnabledSteps = implode('|', array_filter($ajaxEnabledSteps));
+            $ajaxEnabledSteps = implode('|', array_filter($ajaxEnabledSteps ?? []));
 
-            if (empty($ajaxEnabledSteps) || !preg_match('/(' . $ajaxEnabledSteps . ')/i', $event->getStep()->getText())) {
+            if (empty($ajaxEnabledSteps) || !preg_match('/(' . $ajaxEnabledSteps . ')/i', $event->getStep()->getText() ?? '')) {
                 return;
             }
 
@@ -264,9 +264,9 @@ public function handleAjaxAfterStep(AfterStepScope $event)
         }
         try {
             $ajaxEnabledSteps = $this->getMainContext()->getAjaxSteps();
-            $ajaxEnabledSteps = implode('|', array_filter($ajaxEnabledSteps));
+            $ajaxEnabledSteps = implode('|', array_filter($ajaxEnabledSteps ?? []));
 
-            if (empty($ajaxEnabledSteps) || !preg_match('/(' . $ajaxEnabledSteps . ')/i', $event->getStep()->getText())) {
+            if (empty($ajaxEnabledSteps) || !preg_match('/(' . $ajaxEnabledSteps . ')/i', $event->getStep()->getText() ?? '')) {
                 return;
             }
 
@@ -377,7 +377,7 @@ protected function findNamedButton($title)
     {
         $page = $this->getSession()->getPage();
         // See https://mathiasbynens.be/notes/css-escapes
-        $escapedTitle = addcslashes($title, '!"#$%&\'()*+,-./:;<=>?@[\]^`{|}~');
+        $escapedTitle = addcslashes($title ?? '', '!"#$%&\'()*+,-./:;<=>?@[\]^`{|}~');
         $matchedEl = null;
         $searches = [
             ['named', ['link_or_button', "'{$title}'"]],
@@ -406,7 +406,7 @@ protected function findNamedButton($title)
     public function iShouldSeeAButton($negative, $text)
     {
         $button = $this->findNamedButton($text);
-        if (trim($negative)) {
+        if (trim($negative ?? '')) {
             Assert::assertNull($button, sprintf('%s button found', $text));
         } else {
             Assert::assertNotNull($button, sprintf('%s button not found', $text));
@@ -430,9 +430,9 @@ public function stepIPressTheButton($text)
      */
     public function stepIPressTheButtons($text)
     {
-        $buttonNames = explode('|', $text);
+        $buttonNames = explode('|', $text ?? '');
         foreach ($buttonNames as $name) {
-            $button = $this->findNamedButton(trim($name));
+            $button = $this->findNamedButton(trim($name ?? ''));
             if ($button) {
                 break;
             }
@@ -718,14 +718,14 @@ public function iPutABreakpoint()
      */
     public function castRelativeToAbsoluteTime($prefix, $val)
     {
-        $timestamp = strtotime($val);
+        $timestamp = strtotime($val ?? '');
         if (!$timestamp) {
             throw new InvalidArgumentException(sprintf(
                 "Can't resolve '%s' into a valid datetime value",
                 $val
             ));
         }
-        return date($this->timeFormat, $timestamp);
+        return date($this->timeFormat ?? '', $timestamp);
     }
 
     /**
@@ -740,14 +740,14 @@ public function castRelativeToAbsoluteTime($prefix, $val)
      */
     public function castRelativeToAbsoluteDatetime($prefix, $val)
     {
-        $timestamp = strtotime($val);
+        $timestamp = strtotime($val ?? '');
         if (!$timestamp) {
             throw new InvalidArgumentException(sprintf(
                 "Can't resolve '%s' into a valid datetime value",
                 $val
             ));
         }
-        return date($this->datetimeFormat, $timestamp);
+        return date($this->datetimeFormat ?? '', $timestamp);
     }
 
     /**
@@ -762,14 +762,14 @@ public function castRelativeToAbsoluteDatetime($prefix, $val)
      */
     public function castRelativeToAbsoluteDate($prefix, $val)
     {
-        $timestamp = strtotime($val);
+        $timestamp = strtotime($val ?? '');
         if (!$timestamp) {
             throw new InvalidArgumentException(sprintf(
                 "Can't resolve '%s' into a valid datetime value",
                 $val
             ));
         }
-        return date($this->dateFormat, $timestamp);
+        return date($this->dateFormat ?? '', $timestamp);
     }
 
     public function getDateFormat()
@@ -828,7 +828,7 @@ public function stepFieldShouldBeDisabled($name, $type, $negate)
         Assert::assertNotNull($element, sprintf("Element '%s' not found", $name));
 
         $disabledAttribute = $element->getAttribute('disabled');
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             Assert::assertNull($disabledAttribute, sprintf("Failed asserting element '%s' is not disabled", $name));
         } else {
             Assert::assertNotNull($disabledAttribute, sprintf("Failed asserting element '%s' is disabled", $name));
@@ -929,11 +929,11 @@ public function iSeeTextInRegion($negate, $text, $region)
         Assert::assertNotNull($regionObj);
 
         $actual = $regionObj->getText();
-        $actual = preg_replace('/\s+/u', ' ', $actual);
-        $regex  = '/' . preg_quote($text, '/') . '/ui';
+        $actual = preg_replace('/\s+/u', ' ', $actual ?? '');
+        $regex  = '/' . preg_quote($text ?? '', '/') . '/ui';
 
-        if (trim($negate)) {
-            if (preg_match($regex, $actual)) {
+        if (trim($negate ?? '')) {
+            if (preg_match($regex ?? '', $actual ?? '')) {
                 $message = sprintf(
                     'The text "%s" was found in the text of the "%s" region on the page %s.',
                     $text,
@@ -944,7 +944,7 @@ public function iSeeTextInRegion($negate, $text, $region)
                 throw new \Exception($message);
             }
         } else {
-            if (!preg_match($regex, $actual)) {
+            if (!preg_match($regex ?? '', $actual ?? '')) {
                 $message = sprintf(
                     'The text "%s" was not found anywhere in the text of the "%s" region on the page %s.',
                     $text,
@@ -1079,15 +1079,15 @@ public function theTextBeforeAfter($textBefore, $order, $textAfter, $element)
 
         // Check both of the texts exist in the element
         $text = $ele->getText();
-        Assert::assertTrue(strpos($text, $textBefore) !== 'FALSE', sprintf('%s not found in the element %s', $textBefore, $element));
-        Assert::assertTrue(strpos($text, $textAfter) !== 'FALSE', sprintf('%s not found in the element %s', $textAfter, $element));
+        Assert::assertTrue(strpos($text ?? '', $textBefore ?? '') !== 'FALSE', sprintf('%s not found in the element %s', $textBefore, $element));
+        Assert::assertTrue(strpos($text ?? '', $textAfter ?? '') !== 'FALSE', sprintf('%s not found in the element %s', $textAfter, $element));
 
         /// Use strpos to get the position of the first occurrence of the two texts (case-sensitive)
         // and compare them with the given order (before or after)
         if ($order === 'before') {
-            Assert::assertTrue(strpos($text, $textBefore) < strpos($text, $textAfter));
+            Assert::assertTrue(strpos($text ?? '', $textBefore ?? '') < strpos($text ?? '', $textAfter ?? ''));
         } else {
-            Assert::assertTrue(strpos($text, $textBefore) > strpos($text, $textAfter));
+            Assert::assertTrue(strpos($text ?? '', $textBefore ?? '') > strpos($text ?? '', $textAfter ?? ''));
         }
     }
 
@@ -1302,7 +1302,7 @@ public function iShouldSeeTheElement($not, $cssSelector = '')
             $not = '';
             $cssSelector = $not;
         }
-        $sel = str_replace('"', '\\"', $cssSelector);
+        $sel = str_replace('"', '\\"', $cssSelector ?? '');
         $js = <<<JS
 return document.querySelector("$sel");
 JS;
@@ -1330,8 +1330,8 @@ public function iSelectFromTheField($value, $locator, $withJavascript)
             $field->selectOption($value);
         } else {
             $xpath = $field->getXpath();
-            $xpath = str_replace(['"', "\n"], ['\"', ''], $xpath);
-            $value = str_replace('"', '\"', $value);
+            $xpath = str_replace(['"', "\n"], ['\"', ''], $xpath ?? '');
+            $value = str_replace('"', '\"', $value ?? '');
             $js = <<<JS
                 return (function() {
                     let select = document.evaluate("{$xpath}", document).iterateNext();
@@ -1360,8 +1360,8 @@ public function iSelectFromTheField($value, $locator, $withJavascript)
     public function theRenderedHtmlShouldContain($not, $htmlFragment)
     {
         $html = $this->getSession()->getPage()->getOuterHtml();
-        $htmlFragment = str_replace('\"', '"', $htmlFragment);
-        $contains = strpos($html, $htmlFragment) !== false;
+        $htmlFragment = str_replace('\"', '"', $htmlFragment ?? '');
+        $contains = strpos($html ?? '', $htmlFragment ?? '') !== false;
         if ($not) {
             Assert::assertFalse($contains, "HTML fragment {$htmlFragment} was in rendered HTML when it should not have been");
         } else {
@@ -1463,18 +1463,18 @@ public function iPressTheKeyGlobally($keyCombo)
             return;
         }
         $modifier = null;
-        $pos = strpos($keyCombo, '-');
+        $pos = strpos($keyCombo ?? '', '-');
         if ($pos !== false && $pos !== 0) {
-            list($modifier, $char) = explode('-', $keyCombo);
+            list($modifier, $char) = explode('-', $keyCombo ?? '');
         } else {
             $char = $keyCombo;
         }
         // handle special chars e.g. "space"
-        if (defined(WebDriverKeys::class . '::' . strtoupper($char))) {
-            $char = constant(WebDriverKeys::class . '::' . strtoupper($char));
+        if (defined(WebDriverKeys::class . '::' . strtoupper($char ?? ''))) {
+            $char = constant(WebDriverKeys::class . '::' . strtoupper($char ?? ''));
         }
         if ($modifier) {
-            $modifier = strtoupper($modifier);
+            $modifier = strtoupper($modifier ?? '');
             if (defined(WebDriverKeys::class . '::' . $modifier)) {
                 $modifier = constant(WebDriverKeys::class . '::' . $modifier);
             } else {
@@ -1495,13 +1495,13 @@ public function iAttachTheFileToTheField($filename, $locator)
     {
         Assert::assertNotNull($this->fixtureContext, 'FixtureContext was not found so cannot know location of fixture files');
         $path = $this->fixtureContext->getFilesPath() . '/' . $filename;
-        $path = str_replace('//', '/', $path);
+        $path = str_replace('//', '/', $path ?? '');
         Assert::assertNotEmpty($path, 'Fixture files path is empty');
         $field = $this->getElement($locator);
         $filesPath = $this->fixtureContext->getFilesPath();
         if ($filesPath) {
-            $fullPath = rtrim(realpath($filesPath), DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR . $path;
-            if (is_file($fullPath)) {
+            $fullPath = rtrim(realpath($filesPath ?? '') ?? '', DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR . $path;
+            if (is_file($fullPath ?? '')) {
                 $path = $fullPath;
             }
         }
@@ -1526,12 +1526,12 @@ public function iFollowWithJavascript($locator)
         }
         Assert::assertNotNull($link, "Link {$locator} was not found");
         $html = $link->getOuterHtml();
-        preg_match('#href=([\'"])#', $html, $m);
+        preg_match('#href=([\'"])#', $html ?? '', $m);
         $q = $m[1];
-        preg_match("#href={$q}(.+?){$q}#", $html, $m);
-        $href = str_replace("'", "\\'", $m[1]);
-        if (strpos($href, 'http') !== 0) {
-            $href = rtrim($href, '/');
+        preg_match("#href={$q}(.+?){$q}#", $html ?? '', $m);
+        $href = str_replace("'", "\\'", $m[1] ?? '');
+        if (strpos($href ?? '', 'http') !== 0) {
+            $href = rtrim($href ?? '', '/');
             $href = "/{$href}";
         }
         $this->getSession()->executeScript("document.location.href = '{$href}';");
diff --git a/src/Context/EmailContext.php b/src/Context/EmailContext.php
index 2c9a36b1..78d0b0ee 100644
--- a/src/Context/EmailContext.php
+++ b/src/Context/EmailContext.php
@@ -66,7 +66,7 @@ public function thereIsAnEmailFromTo($negate, $direction, $email)
         $to = ($direction == 'to') ? $email : null;
         $from = ($direction == 'from') ? $email : null;
         $match = $this->mailer->findEmail($to, $from);
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             Assert::assertNull($match);
         } else {
             Assert::assertNotNull($match);
@@ -90,7 +90,7 @@ public function thereIsAnEmailFromToTitled($negate, $direction, $email, $subject
         $allTitles = $allMails ? '"' . implode('","', array_map(function ($email) {
             return $email->Subject;
         }, $allMails)) . '"' : null;
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             Assert::assertNull($match);
         } else {
             $msg = sprintf(
@@ -130,7 +130,7 @@ public function thereTheEmailContains($negate, $content)
             $emailContent = $email->PlainContent;
         }
 
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             Assert::assertStringNotContainsString($content, $emailContent);
         } else {
             Assert::assertStringContainsString($content, $emailContent);
@@ -154,8 +154,8 @@ public function thereTheEmailContainsPlainText($content)
 
         $email = $this->lastMatchedEmail;
         $emailContent = ($email->Content) ? ($email->Content) : ($email->PlainContent);
-        $emailPlainText = strip_tags($emailContent);
-        $emailPlainText = preg_replace("/\h+/", " ", $emailPlainText);
+        $emailPlainText = strip_tags($emailContent ?? '');
+        $emailPlainText = preg_replace("/\h+/", " ", $emailPlainText ?? '');
 
         Assert::assertStringContainsString($content, $emailPlainText);
     }
@@ -259,12 +259,12 @@ public function theEmailContainFollowingData($negate, TableNode $table)
             $emailContent = $email->PlainContent;
         }
         // Convert html content to plain text
-        $emailContent = strip_tags($emailContent);
-        $emailContent = preg_replace("/\h+/", " ", $emailContent);
+        $emailContent = strip_tags($emailContent ?? '');
+        $emailContent = preg_replace("/\h+/", " ", $emailContent ?? '');
         $rows = $table->getRows();
 
         // For "should not contain"
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             foreach ($rows as $row) {
                 Assert::assertStringNotContainsString($row[0], $emailContent);
             }
@@ -283,7 +283,7 @@ public function theEmailContainFollowingData($negate, TableNode $table)
     public function thereIsAnEmailTitled($negate, $subject)
     {
         $match = $this->mailer->findEmail(null, null, $subject);
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             Assert::assertNull($match);
         } else {
             $msg = sprintf(
@@ -307,7 +307,7 @@ public function theEmailSentFrom($negate, $from)
         }
 
         $match = $this->lastMatchedEmail;
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             Assert::assertStringNotContainsString($from, $match->From);
         } else {
             Assert::assertStringContainsString($from, $match->From);
@@ -326,7 +326,7 @@ public function theEmailSentTo($negate, $to)
         }
 
         $match = $this->lastMatchedEmail;
-        if (trim($negate)) {
+        if (trim($negate ?? '')) {
             Assert::assertStringNotContainsString($to, $match->To);
         } else {
             Assert::assertStringContainsString($to, $match->To);
@@ -355,7 +355,7 @@ public function iClickOnHttpLinkInEmail($httpText)
         $href = null;
         foreach ($tags as $tag) {
             $linkText = $tag->nodeValue;
-            if (strpos($linkText, $httpText) !== false) {
+            if (strpos($linkText ?? '', $httpText ?? '') !== false) {
                 $href = $linkText;
                 break;
             }
diff --git a/src/Context/FixtureContext.php b/src/Context/FixtureContext.php
index 209c7c5d..198da845 100644
--- a/src/Context/FixtureContext.php
+++ b/src/Context/FixtureContext.php
@@ -257,12 +257,12 @@ public function stepCreateRecordWithData($type, $id, $data)
         $class = $this->convertTypeToClass($type);
         preg_match_all(
             '/"(?<key>[^"]+)"\s*=\s*"(?<value>[^"]+)"/',
-            $data,
+            $data ?? '',
             $matches
         );
         $fields = $this->convertFields(
             $class,
-            array_combine($matches['key'], $matches['value'])
+            array_combine($matches['key'] ?? [], $matches['value'] ?? [])
         );
         $fields = $this->prepareFixture($class, $id, $fields);
         // We should check if this fixture object already exists - if it does, we update it. If not, we create it
@@ -403,20 +403,20 @@ public function stepIAssignObjToObjInTheRelation($type, $value, $relationType, $
         $manyField = null;
         $oneField = null;
         if ($relationObj->manyMany()) {
-            $manyField = array_search($class, $relationObj->manyMany());
-            if ($manyField && strlen($relationName) > 0) {
+            $manyField = array_search($class, $relationObj->manyMany() ?? []);
+            if ($manyField && strlen($relationName ?? '') > 0) {
                 $manyField = $relationName;
             }
         }
         if (empty($manyField) && $relationObj->hasMany(true)) {
-            $manyField = array_search($class, $relationObj->hasMany());
-            if ($manyField && strlen($relationName) > 0) {
+            $manyField = array_search($class, $relationObj->hasMany() ?? []);
+            if ($manyField && strlen($relationName ?? '') > 0) {
                 $manyField = $relationName;
             }
         }
         if (empty($manyField) && $relationObj->hasOne()) {
-            $oneField = array_search($class, $relationObj->hasOne());
-            if ($oneField && strlen($relationName) > 0) {
+            $oneField = array_search($class, $relationObj->hasOne() ?? []);
+            if ($oneField && strlen($relationName ?? '') > 0) {
                 $oneField = $relationName;
             }
         }
@@ -555,12 +555,12 @@ public function stepCreateMemberWithGroupAndData($id, $groupId, $data)
     {
         preg_match_all(
             '/"(?<key>[^"]+)"\s*=\s*"(?<value>[^"]+)"/',
-            $data,
+            $data ?? '',
             $matches
         );
         $fields = $this->convertFields(
             Member::class,
-            array_combine($matches['key'], $matches['value'])
+            array_combine($matches['key'] ?? [], $matches['value'] ?? [])
         );
 
         /** @var Group $group */
@@ -587,7 +587,7 @@ public function stepCreateMemberWithGroupAndData($id, $groupId, $data)
     public function stepCreateGroupWithPermissions($id, $permissionStr)
     {
         // Convert natural language permissions to codes
-        preg_match_all('/"([^"]+)"/', $permissionStr, $matches);
+        preg_match_all('/"([^"]+)"/', $permissionStr ?? '', $matches);
         $permissions = $matches[1];
         $codes = Permission::get_codes(false);
 
@@ -652,7 +652,7 @@ public function iAddAnExtensionToTheClass($extension, $class)
     {
         // Validate the extension
         Assert::assertTrue(
-            class_exists($extension) && is_subclass_of($extension, Extension::class),
+            class_exists($extension ?? '') && is_subclass_of($extension, Extension::class),
             'Given extension does not extend Extension'
         );
 
@@ -662,7 +662,7 @@ class_exists($extension) && is_subclass_of($extension, Extension::class),
         $targetClass::add_extension($extension);
 
         // Write config for this extension too...
-        $snakedExtension = strtolower(str_replace('\\', '-', $extension));
+        $snakedExtension = strtolower(str_replace('\\', '-', $extension ?? '') ?? '');
         $config = <<<YAML
 ---
 Name: testonly-enable-extension-$snakedExtension
@@ -674,7 +674,7 @@ class_exists($extension) && is_subclass_of($extension, Extension::class),
 
         $filename = 'enable-' . $snakedExtension . '.yml';
         $destPath = $this->getDestinationConfigFolder($filename);
-        file_put_contents($destPath, $config);
+        file_put_contents($destPath ?? '', $config);
 
         // Remember to cleanup...
         $this->activatedConfigFiles[] = $destPath;
@@ -741,8 +741,8 @@ public function stepThereShouldBeAFileWithTuple($filename, $hash)
      */
     public function lookupFixtureReference($string)
     {
-        if (preg_match('/^=>/', $string)) {
-            list($className, $identifier) = explode('.', preg_replace('/^=>/', '', $string), 2);
+        if (preg_match('/^=>/', $string ?? '')) {
+            list($className, $identifier) = explode('.', preg_replace('/^=>/', '', $string ?? '') ?? '', 2);
             $id = $this->getFixtureFactory()->getId($className, $identifier);
             if (!$id) {
                 throw new InvalidArgumentException(sprintf(
@@ -768,7 +768,7 @@ public function aRecordWasLastEditedRelative($type, $id, $mod, $time)
         $class = $this->convertTypeToClass($type);
         $fields = $this->prepareFixture($class, $id);
         $record = $this->getFixtureFactory()->createObject($class, $id, $fields);
-        $date = date("Y-m-d H:i:s", strtotime($time));
+        $date = date("Y-m-d H:i:s", strtotime($time ?? ''));
         $table = $record->baseTable();
         $field = ($mod == 'created') ? 'Created' : 'LastEdited';
         DB::prepared_query(
@@ -821,8 +821,8 @@ protected function prepareAsset($class, $identifier, $data = null)
 
 
         $relativeTargetPath = (isset($data['Filename'])) ? $data['Filename'] : $identifier;
-        $relativeTargetPath = preg_replace('/^' . ASSETS_DIR . '\/?/', '', $relativeTargetPath);
-        $sourcePath = $this->joinPaths($this->getFilesPath(), basename($relativeTargetPath));
+        $relativeTargetPath = preg_replace('/^' . ASSETS_DIR . '\/?/', '', $relativeTargetPath ?? '');
+        $sourcePath = $this->joinPaths($this->getFilesPath(), basename($relativeTargetPath ?? ''));
 
         // Create file or folder on filesystem
         if ($class == 'SilverStripe\\Assets\\Folder' || is_subclass_of($class, 'SilverStripe\\Assets\\Folder')) {
@@ -830,7 +830,7 @@ protected function prepareAsset($class, $identifier, $data = null)
             $data['ID'] = $parent->ID;
         } else {
             // Check file exists
-            if (!file_exists($sourcePath)) {
+            if (!file_exists($sourcePath ?? '')) {
                 throw new InvalidArgumentException(sprintf(
                     'Source file for "%s" cannot be found in "%s"',
                     $relativeTargetPath,
@@ -840,8 +840,8 @@ protected function prepareAsset($class, $identifier, $data = null)
 
             // Get parent
             $parentID = 0;
-            if (strstr($relativeTargetPath, '/')) {
-                $folderName = dirname($relativeTargetPath);
+            if (strstr($relativeTargetPath ?? '', '/')) {
+                $folderName = dirname($relativeTargetPath ?? '');
                 $parent = Folder::find_or_make($folderName);
                 if ($parent) {
                     $parentID = $parent->ID;
@@ -865,7 +865,7 @@ protected function prepareAsset($class, $identifier, $data = null)
             $data['FileVariant'] = $asset['Variant'];
         }
         if (!isset($data['Name'])) {
-            $data['Name'] = basename($relativeTargetPath);
+            $data['Name'] = basename($relativeTargetPath ?? '');
         }
 
         // Save assets
@@ -894,17 +894,17 @@ protected function getAssetStore()
      */
     protected function convertTypeToClass($type)
     {
-        $type = trim($type);
+        $type = trim($type ?? '');
 
         // Try direct mapping
-        $class = str_replace(' ', '', ucwords($type));
-        if (class_exists($class) && is_subclass_of($class, DataObject::class)) {
+        $class = str_replace(' ', '', ucwords($type ?? ''));
+        if (class_exists($class ?? '') && is_subclass_of($class, DataObject::class)) {
             return ClassInfo::class_name($class);
         }
 
         // Fall back to singular names
-        foreach (array_values(ClassInfo::subclassesFor(DataObject::class)) as $candidate) {
-            if (class_exists($candidate) && strcasecmp(singleton($candidate)->singular_name(), $type) === 0) {
+        foreach (array_values(ClassInfo::subclassesFor(DataObject::class) ?? []) as $candidate) {
+            if (class_exists($candidate ?? '') && strcasecmp(singleton($candidate)->singular_name() ?? '', $type ?? '') === 0) {
                 return $candidate;
             }
         }
@@ -927,7 +927,7 @@ protected function convertFields($class, $fields)
     {
         $labels = singleton($class)->fieldLabels();
         foreach ($fields as $fieldName => $fieldVal) {
-            if ($fieldLabelKey = array_search($fieldName, $labels)) {
+            if ($fieldLabelKey = array_search($fieldName, $labels ?? [])) {
                 unset($fields[$fieldName]);
                 $fields[$labels[$fieldLabelKey]] = $fieldVal;
             }
@@ -943,9 +943,9 @@ protected function joinPaths()
             $paths = array_merge($paths, (array)$arg);
         }
         foreach ($paths as &$path) {
-            $path = trim($path, '/');
+            $path = trim($path ?? '', '/');
         }
-        if (substr($args[0], 0, 1) == '/') {
+        if (substr($args[0] ?? '', 0, 1) == '/') {
             $paths[0] = '/' . $paths[0];
         }
         return join('/', $paths);
@@ -959,8 +959,8 @@ protected function clearConfigFiles()
         }
 
         foreach ($this->activatedConfigFiles as $configFile) {
-            if (file_exists($configFile)) {
-                unlink($configFile);
+            if (file_exists($configFile ?? '')) {
+                unlink($configFile ?? '');
             }
         }
         $this->activatedConfigFiles = [];
diff --git a/src/Context/LoginContext.php b/src/Context/LoginContext.php
index dbed6446..1a96cf75 100644
--- a/src/Context/LoginContext.php
+++ b/src/Context/LoginContext.php
@@ -32,7 +32,7 @@ public function stepIAmLoggedIn()
 
         $this->getMainContext()->getSession()->visit($adminUrl);
 
-        if (0 == strpos($this->getMainContext()->getSession()->getCurrentUrl(), $loginUrl)) {
+        if (0 == strpos($this->getMainContext()->getSession()->getCurrentUrl() ?? '', $loginUrl ?? '')) {
             $this->stepILogInWith('admin', 'password');
             Assert::assertStringStartsWith($adminUrl, $this->getMainContext()->getSession()->getCurrentUrl());
         }
diff --git a/src/Context/SilverStripeContext.php b/src/Context/SilverStripeContext.php
index 54f87987..d85c55c6 100644
--- a/src/Context/SilverStripeContext.php
+++ b/src/Context/SilverStripeContext.php
@@ -191,7 +191,7 @@ public function getRegionObj($region)
             $regionObj = $this->getSession()->getPage()->find(
                 'css',
                 // Escape CSS selector
-                (false !== strpos($region, "'")) ? str_replace("'", "\\'", $region) : $region
+                (false !== strpos($region ?? '', "'")) ? str_replace("'", "\\'", $region) : $region
             );
             if ($regionObj) {
                 return $regionObj;
@@ -203,7 +203,7 @@ public function getRegionObj($region)
         // Fall back to region identified by data-title.
         // Only apply if no double quotes exist in search string,
         // which would break the CSS selector.
-        if (false === strpos($region, '"')) {
+        if (false === strpos($region ?? '', '"')) {
             $regionObj = $this->getSession()->getPage()->find(
                 'css',
                 '[data-title="' . $region . '"]'
@@ -217,7 +217,7 @@ public function getRegionObj($region)
         if (!$this->regionMap) {
             throw new \LogicException("Cannot find 'region_map' in the behat.yml");
         }
-        if (!array_key_exists($region, $this->regionMap)) {
+        if (!array_key_exists($region, $this->regionMap ?? [])) {
             throw new \LogicException("Cannot find the specified region in the behat.yml");
         }
         $regionObj = $this->getSession()->getPage()->find('css', $region);
@@ -265,7 +265,7 @@ public function before(BeforeScenarioScope $event)
         }
 
         if ($screenSize = Environment::getEnv('BEHAT_SCREEN_SIZE')) {
-            list($screenWidth, $screenHeight) = explode('x', $screenSize);
+            list($screenWidth, $screenHeight) = explode('x', $screenSize ?? '');
             $this->getSession()->resizeWindow((int)$screenWidth, (int)$screenHeight);
         } else {
             $this->getSession()->resizeWindow(1024, 768);
@@ -312,7 +312,7 @@ public function waitResponsesAfterStep(AfterStepScope $event)
     public function getTestSessionState()
     {
         $extraParams = array();
-        parse_str(Environment::getEnv('TESTSESSION_PARAMS'), $extraParams);
+        parse_str(Environment::getEnv('TESTSESSION_PARAMS') ?? '', $extraParams);
         return array_merge(
             array(
                 'database' => $this->databaseName,
@@ -330,13 +330,13 @@ public function getTestSessionState()
      */
     public function parseUrl($url)
     {
-        $url = parse_url($url);
+        $url = parse_url($url ?? '');
         $url['vars'] = array();
         if (!isset($url['fragment'])) {
             $url['fragment'] = null;
         }
         if (isset($url['query'])) {
-            parse_str($url['query'], $url['vars']);
+            parse_str($url['query'] ?? '', $url['vars']);
         }
 
         return $url;
@@ -401,7 +401,7 @@ public function joinUrlParts($part = null)
 
         $parts = func_get_args();
         $trimSlashes = function (&$part) {
-            $part = trim($part, '/');
+            $part = trim($part ?? '', '/');
         };
         array_walk($parts, $trimSlashes);
 
@@ -600,7 +600,7 @@ public function selectOptionWithJavascript($select, $option)
         $value = $field->getValue();
         $newValue = $opt->getAttribute('value');
         if (is_array($value)) {
-            if (!in_array($newValue, $value)) {
+            if (!in_array($newValue, $value ?? [])) {
                 $value[] = $newValue;
             }
         } else {
diff --git a/src/Controllers/ModuleCommandTrait.php b/src/Controllers/ModuleCommandTrait.php
index a4a572c4..d612b6dc 100644
--- a/src/Controllers/ModuleCommandTrait.php
+++ b/src/Controllers/ModuleCommandTrait.php
@@ -17,8 +17,8 @@ trait ModuleCommandTrait
      */
     protected function getModule($name, $error = true)
     {
-        if (strpos($name, '@') === 0) {
-            $name = substr($name, 1);
+        if (strpos($name ?? '', '@') === 0) {
+            $name = substr($name ?? '', 1);
         }
         $module = ModuleLoader::inst()->getManifest()->getModule($name);
         if (!$module && $error) {
diff --git a/src/Controllers/ModuleInitialisationController.php b/src/Controllers/ModuleInitialisationController.php
index e8ba23eb..15609bb0 100644
--- a/src/Controllers/ModuleInitialisationController.php
+++ b/src/Controllers/ModuleInitialisationController.php
@@ -139,10 +139,10 @@ protected function initFeaturesPath(OutputInterface $output, Module $module)
         // Create feature_path
         $features = $this->container->getParameter('silverstripe_extension.context.features_path');
         $fullPath = $module->getResourcePath($features);
-        if (is_dir($fullPath)) {
+        if (is_dir($fullPath ?? '')) {
             return;
         }
-        mkdir($fullPath, 0777, true);
+        mkdir($fullPath ?? '', 0777, true);
         $output->writeln(
             "<info>{$fullPath}</info> - <comment>place your *.feature files here</comment>"
         );
@@ -165,13 +165,13 @@ protected function initClassPath(OutputInterface $output, Module $module, $names
     {
         $classesPath = $this->container->getParameter('silverstripe_extension.context.class_path');
         $dirPath = $module->getResourcePath($classesPath);
-        if (!is_dir($dirPath)) {
-            mkdir($dirPath, 0777, true);
+        if (!is_dir($dirPath ?? '')) {
+            mkdir($dirPath ?? '', 0777, true);
         }
 
         // Scaffold base context file
         $classPath = "{$dirPath}/FeatureContext.php";
-        if (is_file($classPath)) {
+        if (is_file($classPath ?? '')) {
             return;
         }
 
@@ -185,7 +185,7 @@ protected function initClassPath(OutputInterface $output, Module $module, $names
             'ClassName' => $class,
         ]);
         $classContent = $obj->renderWith(__DIR__.'/../../templates/FeatureContext.ss');
-        file_put_contents($classPath, $classContent);
+        file_put_contents($classPath ?? '', $classContent);
 
         // Log
         $output->writeln(
@@ -194,12 +194,12 @@ protected function initClassPath(OutputInterface $output, Module $module, $names
 
         // Add to composer json
         $composerFile = $module->getResourcePath('composer.json');
-        if (!file_exists($composerFile)) {
+        if (!file_exists($composerFile ?? '')) {
             return;
         }
 
         // Add autoload directive to composer
-        $composerData = json_decode(file_get_contents($composerFile), true);
+        $composerData = json_decode(file_get_contents($composerFile ?? '') ?? '', true);
         if (json_last_error()) {
             throw new Exception(json_last_error_msg());
         }
@@ -211,7 +211,7 @@ protected function initClassPath(OutputInterface $output, Module $module, $names
         }
         $composerData['autoload']['psr-4']["{$fullNamespace}\\"] = $classesPath;
         file_put_contents(
-            $composerFile,
+            $composerFile ?? '',
             json_encode($composerData, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES)
         );
 
@@ -239,7 +239,7 @@ protected function getFixtureClass($namespaceRoot)
     protected function getFixtureNamespace($namespaceRoot)
     {
         $namespaceSuffix = $this->container->getParameter('silverstripe_extension.context.namespace_suffix');
-        return trim($namespaceRoot, '/\\') . '\\' . $namespaceSuffix;
+        return trim($namespaceRoot ?? '', '/\\') . '\\' . $namespaceSuffix;
     }
 
     /**
@@ -252,7 +252,7 @@ protected function getFixtureNamespace($namespaceRoot)
     protected function initConfig($output, $module, $namespaceRoot)
     {
         $configPath = $module->getResourcePath('behat.yml');
-        if (file_exists($configPath)) {
+        if (file_exists($configPath ?? '')) {
             return;
         }
         $class = $this->getFixtureClass($namespaceRoot);
@@ -279,7 +279,7 @@ protected function initConfig($output, $module, $namespaceRoot)
                 ]
             ]
         ];
-        file_put_contents($configPath, Yaml::dump($data, 99999999, 2));
+        file_put_contents($configPath ?? '', Yaml::dump($data, 99999999, 2));
 
         $output->writeln(
             "<info>{$configPath}</info> - <comment>default behat.yml created</comment>"
diff --git a/src/Controllers/ModuleSuiteLocator.php b/src/Controllers/ModuleSuiteLocator.php
index a78eb959..63265120 100644
--- a/src/Controllers/ModuleSuiteLocator.php
+++ b/src/Controllers/ModuleSuiteLocator.php
@@ -158,7 +158,7 @@ protected function findModuleConfig(Module $module)
         // Find all candidate paths
         foreach ([ "{$path}/", "{$path}/{$pathSuffix}"] as $parent) {
             foreach ([$parent.'behat.yml', $parent.'.behat.yml'] as $candidate) {
-                if (file_exists($candidate)) {
+                if (file_exists($candidate ?? '')) {
                     return $candidate;
                 }
             }
@@ -178,7 +178,7 @@ protected function loadSuiteConfiguration($suite, Module $module)
     {
         $path = $this->findModuleConfig($module);
         $yamlParser = new Parser();
-        $config = $yamlParser->parse(file_get_contents($path));
+        $config = $yamlParser->parse(file_get_contents($path ?? ''));
         if (empty($config['default']['suites'][$suite])) {
             throw new Exception("Path {$path} does not contain default.suites.{$suite} config");
         }
diff --git a/src/Extension.php b/src/Extension.php
index 24dffb17..7658b2b4 100644
--- a/src/Extension.php
+++ b/src/Extension.php
@@ -63,7 +63,7 @@ public function initialize(ExtensionManager $extensionManager)
         ];
 
         foreach ($options as $file) {
-            if (file_exists($file)) {
+            if (file_exists($file ?? '')) {
                 require_once $file;
                 $found = true;
                 break;
diff --git a/src/Utility/DebugTools.php b/src/Utility/DebugTools.php
index ca0a751f..6fa2a7ca 100644
--- a/src/Utility/DebugTools.php
+++ b/src/Utility/DebugTools.php
@@ -118,9 +118,9 @@ public function dumpRenderedHtml(StepScope $event)
         // prefix with zz_ so that it alpha sorts in the directory lower than screenshots which
         // will typically be referred to far more often.  This is mainly for when you have
         // enabled `dumpRenderedHtmlAfterEveryStep`
-        $path = sprintf('%s/zz_%s_%d.html', $path, basename($feature->getFile()), $step->getLine());
+        $path = sprintf('%s/zz_%s_%d.html', $path, basename($feature->getFile() ?? ''), $step->getLine());
         $html = $this->getSession()->getPage()->getOuterHtml();
-        file_put_contents($path, $html);
+        file_put_contents($path ?? '', $html);
         $this->logMessage(sprintf('Saving HTML into %s', $path));
     }
 
@@ -143,9 +143,9 @@ public function takeScreenshot(StepScope $event)
         if (!$path) {
             return;
         }
-        $path = sprintf('%s/%s_%d.png', $path, basename($feature->getFile()), $step->getLine());
+        $path = sprintf('%s/%s_%d.png', $path, basename($feature->getFile() ?? ''), $step->getLine());
         $screenshot = $driver->getScreenshot();
-        file_put_contents($path, $screenshot);
+        file_put_contents($path ?? '', $screenshot);
         $this->logMessage(sprintf('Saving screenshot into %s', $path));
     }
 
@@ -161,16 +161,16 @@ private function prepareScreenshotPath()
             return;
         }
         Filesystem::makeFolder($path);
-        $path = realpath($path);
-        if (!file_exists($path)) {
+        $path = realpath($path ?? '');
+        if (!file_exists($path ?? '')) {
             $this->logMessage(sprintf('"%s" is not valid directory and failed to create it', $path));
             return;
         }
-        if (file_exists($path) && !is_dir($path)) {
+        if (file_exists($path ?? '') && !is_dir($path ?? '')) {
             $this->logMessage(sprintf('"%s" is not valid directory', $path));
             return;
         }
-        if (file_exists($path) && !is_writable($path)) {
+        if (file_exists($path ?? '') && !is_writable($path ?? '')) {
             $this->logMessage(sprintf('"%s" directory is not writable', $path));
             return;
         }
diff --git a/src/Utility/RetryableCallHandler.php b/src/Utility/RetryableCallHandler.php
index e7d832de..7a86b53a 100644
--- a/src/Utility/RetryableCallHandler.php
+++ b/src/Utility/RetryableCallHandler.php
@@ -112,10 +112,10 @@ private function executeCall(Call $call)
             // Determine whether to call with retries
             if ($retry) {
                 $return = $this->retryThrowable(function () use ($callable, $arguments) {
-                    return call_user_func_array($callable, $arguments);
+                    return call_user_func_array($callable, $arguments ?? []);
                 }, $this->retrySeconds);
             } else {
-                $return = call_user_func_array($callable, $arguments);
+                $return = call_user_func_array($callable, $arguments ?? []);
             }
         } catch (Exception $caught) {
             $exception = $caught;
@@ -144,7 +144,7 @@ private function getBufferedStdOut()
     private function startErrorAndOutputBuffering(Call $call)
     {
         $errorReporting = $call->getErrorReportingLevel() ? : $this->errorReportingLevel;
-        set_error_handler(array($this, 'handleError'), $errorReporting);
+        set_error_handler(array($this, 'handleError'), $errorReporting ?? 0);
         $this->obStarted = ob_start();
     }
 
diff --git a/src/Utility/TestMailer.php b/src/Utility/TestMailer.php
index 19646acc..5f61b15e 100644
--- a/src/Utility/TestMailer.php
+++ b/src/Utility/TestMailer.php
@@ -38,7 +38,7 @@ public function findEmail($to = null, $from = null, $subject = null, $content =
     {
         $matches = $this->findEmails($to, $from, $subject, $content);
                 //got the count of matches emails
-                $emailCount = count($matches);
+                $emailCount = count($matches ?? []);
                 //get the last(latest) one
         return $matches ? $matches[$emailCount-1] : null;
     }
@@ -70,7 +70,7 @@ public function findEmails($to = null, $from = null, $subject = null, $content =
                 $value = (isset($args[$i])) ? $args[$i] : null;
                 if ($value) {
                     if ($value[0] == '/') {
-                        $matched = preg_match($value, $email->$field);
+                        $matched = preg_match($value ?? '', $email->$field ?? '');
                     } else {
                         $matched = ($value == $email->$field);
                     }
@@ -93,7 +93,7 @@ protected function saveEmail($data)
         if (!isset($state->emails)) {
             $state->emails = array();
         }
-        $state->emails[] = array_filter($data);
+        $state->emails[] = array_filter($data ?? []);
         $this->testSessionEnvironment->applyState($state);
     }
 }