diff --git a/CHANGES.md b/CHANGES.md
index f22aa94..3e2da0f 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,10 @@ moodle-local_differentiator
 Changes
 -------
 
+### Unreleased
+
+* 2024-03-02 - Fixing some linter errors.
+
 ### v4.3-r2
 
 * 2024-03-02 - Adding Behat tests.
diff --git a/classes/differentiator.php b/classes/differentiator.php
index 7fdff36..fc451e2 100644
--- a/classes/differentiator.php
+++ b/classes/differentiator.php
@@ -47,7 +47,7 @@ public function __construct() {
      * @return \moodle_url
      * @throws \moodle_exception
      */
-    public function make_url(string $subpath, array $params = null) : \moodle_url {
+    public function make_url(string $subpath, array $params = null): \moodle_url {
         $path = '/local/differentiator/view.php/' . $subpath;
         return new \moodle_url($path, $params);
     }
@@ -59,7 +59,7 @@ public function make_url(string $subpath, array $params = null) : \moodle_url {
      * @return bool
      * @throws \coding_exception
      */
-    public function user_has_capability(string $capability) : bool {
+    public function user_has_capability(string $capability): bool {
         return \has_capability($capability, $this->context);
     }
 
diff --git a/classes/external/learninggoal.php b/classes/external/learninggoal.php
index f26664b..071ceb6 100644
--- a/classes/external/learninggoal.php
+++ b/classes/external/learninggoal.php
@@ -33,6 +33,20 @@
 
 defined('MOODLE_INTERNAL') || die();
 
+// This work-around is required until Moodle 4.2 is the lowest version we support.
+if (class_exists('core_external\external_api') && class_exists('core_external\external_function_parameters')
+    && class_exists('core_external\external_value') && class_exists('core_external\external_multiple_structure')) {
+    class_alias('core_external\external_api', '\local_differentiator_external_api_class_alias');
+    class_alias('core_external\external_function_parameters', '\local_differentiator_external_function_parameters_class_alias');
+    class_alias('core_external\external_value', '\local_differentiator_external_value_class_alias');
+    class_alias('core_external\external_multiple_structure', '\local_differentiator_external_multiple_structure_class_alias');
+} else {
+    class_alias('external_api', '\local_differentiator_external_api_class_alias');
+    class_alias('external_function_parameters', '\local_differentiator_external_function_parameters_class_alias');
+    class_alias('external_value', '\local_differentiator_external_value_class_alias');
+    class_alias('external_multiple_structure', '\local_differentiator_external_multiple_structure_class_alias');
+}
+
 require_once($CFG->libdir.'/externallib.php');
 
 /**
@@ -51,8 +65,8 @@ class learninggoal extends \external_api {
      */
     public static function get_learninggoal_parameters() {
         return new external_function_parameters([
-            'userid' => new external_value(PARAM_INT, 'userid'),
-            'learninggoalid' => new external_value(PARAM_INT, 'learninggoalid'),
+            'userid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'userid'),
+            'learninggoalid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'learninggoalid'),
         ]);
     }
 
@@ -64,19 +78,19 @@ public static function get_learninggoal_parameters() {
      */
     public static function save_learninggoal_parameters() {
         return new external_function_parameters([
-            'userid' => new external_value(PARAM_INT, 'userid'),
-            'learninggoalid' => new external_value(PARAM_INT, 'id of the learning goal'),
-            'name' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'pre_thinking_skill' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'thinking_skill' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'content' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'subject' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'pre_resource' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'resource' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'pre_product' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'product' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'pre_group' => new external_value(PARAM_TEXT, 'name of the learning goal'),
-            'group' => new external_value(PARAM_TEXT, 'name of the learning goal'),
+            'userid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'userid'),
+            'learninggoalid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'id of the learning goal'),
+            'name' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'pre_thinking_skill' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'thinking_skill' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'content' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'subject' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'pre_resource' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'resource' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'pre_product' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'product' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'pre_group' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
+            'group' => new \local_differentiator_external_value_class_alias(PARAM_TEXT, 'name of the learning goal'),
         ]);
     }
 
@@ -88,8 +102,8 @@ public static function save_learninggoal_parameters() {
      */
     public static function delete_learninggoal_parameters() {
         return new external_function_parameters([
-            'userid' => new external_value(PARAM_INT, 'userid'),
-            'learninggoalid' => new external_value(PARAM_INT, 'learninggoalid'),
+            'userid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'userid'),
+            'learninggoalid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'learninggoalid'),
         ]);
     }
 
@@ -101,8 +115,8 @@ public static function delete_learninggoal_parameters() {
      */
     public static function duplicate_learninggoal_parameters() {
         return new external_function_parameters([
-            'userid' => new external_value(PARAM_INT, 'userid'),
-            'learninggoalid' => new external_value(PARAM_INT, 'learninggoalid'),
+            'userid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'userid'),
+            'learninggoalid' => new \local_differentiator_external_value_class_alias(PARAM_INT, 'learninggoalid'),
         ]);
     }
 
@@ -113,7 +127,7 @@ public static function duplicate_learninggoal_parameters() {
      * @return external_multiple_structure
      */
     public static function get_learninggoal_returns() {
-        return new external_multiple_structure(
+        return new \local_differentiator_external_multiple_structure_class_alias(
             exporter\learninggoal::get_read_structure()
         );
     }
diff --git a/classes/form/form_controller.php b/classes/form/form_controller.php
index 167199c..85dfb2b 100644
--- a/classes/form/form_controller.php
+++ b/classes/form/form_controller.php
@@ -114,7 +114,7 @@ public function get_message() {
      *
      * @return bool
      */
-    public function success() : bool {
+    public function success(): bool {
         return $this->formsubmittedsuccess;
     }
 
@@ -131,7 +131,7 @@ abstract protected function build_customdata();
      * @param \stdClass $data validated data from form
      * @return bool
      */
-    abstract protected function handle_submit(\stdClass $data) : bool;
+    abstract protected function handle_submit(\stdClass $data): bool;
 
     /**
      * First display of the form.
diff --git a/classes/form/learninggoal_edit_controller.php b/classes/form/learninggoal_edit_controller.php
index 00ce36f..bec56db 100644
--- a/classes/form/learninggoal_edit_controller.php
+++ b/classes/form/learninggoal_edit_controller.php
@@ -71,7 +71,7 @@ protected function build_customdata() {
      * @return bool
      * @throws \dml_exception
      */
-    protected function handle_submit(\stdClass $data) : bool {
+    protected function handle_submit(\stdClass $data): bool {
         global $DB;
 
         if ($this->learninggoalid && $data->learninggoalid != $this->learninggoalid) {
diff --git a/tests/behat/add.feature b/tests/behat/add.feature
index 7113f81..e68ecb4 100644
--- a/tests/behat/add.feature
+++ b/tests/behat/add.feature
@@ -5,10 +5,9 @@ Feature: Access differentiator and add a learning goal.
   Scenario: Access a differentiator and add a learning goal
     Given I log in as "admin"
     And I am on the "Differentiator" "local_differentiator > Differentiator" page
-    And I press "Add a new goal"
+    When I press "Add a new goal"
     And I set the field with xpath "//div[@class='learninggoals-edit-add-form']//input[@type='text']" to "Learning goal 1 (en)"
     And I set the field with xpath "//p[2]//input[@type='text'][4]" to "Quentin Tarantino films"
     And I press "Save"
     Then I should see "Learning goal 1 (en)"
     And I should see "Students will remember the big idea of the Quentin Tarantino films using a textbook and create an essay in groups of one."
-
diff --git a/vue/webpack.config.js b/vue/webpack.config.js
index b17fb11..e8a9afc 100644
--- a/vue/webpack.config.js
+++ b/vue/webpack.config.js
@@ -51,11 +51,11 @@ module.exports = (env, options) => {
             noInfo: true,
             overlay: true,
             headers: {
-                'Access-Control-Allow-Origin': '\*'
+                'Access-Control-Allow-Origin': '*'
             },
             disableHostCheck: true,
             https: true,
-            public: 'https://127.0.0.1:8080',
+            "public": 'https://127.0.0.1:8080',
             hot: true,
         },
         performance: {
@@ -123,7 +123,7 @@ module.exports = (env, options) => {
                     }
                 }),
             ]
-        }
+        };
     }
 
     return exports;