controllers: Fix crash if controller mapping has no module

src/controllers/controller.cpp

@@ -74,7 +74,11 @@ bool Controller::applyPreset(bool initializeScripts) {
         m_pEngine->initializeScripts(scriptFiles);
     }
 
-    if (initializeScripts) {
+    // QFileInfo does not have a isValid/isEmpty/isNull method to check if it
+    // actually contains a reference, so we check if the filePath is empty as a
+    // workaround.
+    // See https://stackoverflow.com/a/45652741/1455128 for details.
+    if (initializeScripts && !pPreset->moduleFileInfo().filePath().isEmpty()) {
         m_pEngine->loadModule(pPreset->moduleFileInfo());
     }
     return success;

src/controllers/controllerpresetfilehandler.cpp

@@ -146,7 +146,18 @@ void ControllerPresetFileHandler::addScriptFilesToPreset(
     }
 
     QString moduleFileName = controller.firstChildElement("module").text();
-    preset->setModuleFileInfo(preset->dirPath().absoluteFilePath(moduleFileName));
+
+    if (moduleFileName.isEmpty()) {
+        return;
+    }
+
+    QFileInfo moduleFileInfo(preset->dirPath().absoluteFilePath(moduleFileName));
+    if (!moduleFileInfo.isFile()) {
+        qWarning() << "Controller Module is not a file:" << moduleFileInfo.absoluteFilePath();
+        return;
+    }
+
+    preset->setModuleFileInfo(moduleFileInfo);
 }
 
 bool ControllerPresetFileHandler::writeDocument(

src/controllers/engine/controllerengine.cpp

@@ -230,6 +230,17 @@ void ControllerEngine::uninitializeScriptEngine() {
 }
 
 void ControllerEngine::loadModule(QFileInfo moduleFileInfo) {
+    // QFileInfo does not have a isValid/isEmpty/isNull method to check if it
+    // actually contains a reference, so we check if the filePath is empty as a
+    // workaround.
+    // See https://stackoverflow.com/a/45652741/1455128 for details.
+    VERIFY_OR_DEBUG_ASSERT(!moduleFileInfo.filePath().isEmpty()) {
+        return;
+    }
+
+    VERIFY_OR_DEBUG_ASSERT(moduleFileInfo.isFile()) {
+        return;
+    }
 #if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)
     m_moduleFileInfo = moduleFileInfo;
 
@@ -318,7 +329,14 @@ void ControllerEngine::reloadScripts() {
 
     qDebug() << "Re-initializing scripts";
     initializeScripts(m_lastScriptFiles);
-    loadModule(m_moduleFileInfo);
+
+    // QFileInfo does not have a isValid/isEmpty/isNull method to check if it
+    // actually contains a reference, so we check if the filePath is empty as a
+    // workaround.
+    // See https://stackoverflow.com/a/45652741/1455128 for details.
+    if (!m_moduleFileInfo.filePath().isEmpty()) {
+        loadModule(m_moduleFileInfo);
+    }
 }
 
 void ControllerEngine::initializeScripts(const QList<ControllerPreset::ScriptFileInfo>& scripts) {