Delete the cached mappings if they are empty or corrupt

app/settings/mappingfetcher.cpp

@@ -32,9 +32,14 @@ void MappingFetcher::start()
 
     // Only download the file if it's newer than what we have
     QFileInfo existingFileInfo = Path::getCacheFileInfo("gamecontrollerdb.txt");
-    if (existingFileInfo.exists() && existingFileInfo.size() > 0) {
+    if (existingFileInfo.exists()) {
+        if (existingFileInfo.size() > 0) {
             request.setHeader(QNetworkRequest::IfModifiedSinceHeader, existingFileInfo.lastModified().toUTC());
         }
+        else {
+            Path::deleteCacheFile("gamecontrollerdb.txt");
+        }
+    }
 
     // We'll get a callback when this is finished
     m_Nam.get(request);

app/settings/mappingmanager.cpp

@@ -72,15 +72,25 @@ void MappingManager::applyMappings()
     if (!mappingData.isEmpty()) {
         int newMappings = SDL_GameControllerAddMappingsFromRW(
                     SDL_RWFromConstMem(mappingData.constData(), mappingData.size()), 1);
+
+        if (newMappings > 0) {
+            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                        "Loaded %d new gamepad mappings",
+                        newMappings);
+        }
+        else {
             if (newMappings < 0) {
                 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
                              "Error loading gamepad mappings: %s",
                              SDL_GetError());
             }
-        else {
+            else if (newMappings == 0) {
-            SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
+                SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION,
-                        "Loaded %d new gamepad mappings",
+                            "0 new mappings found in gamecontrollerdb.txt. Is it corrupt?");
-                        newMappings);
+            }
+
+            // Try deleting the cached mapping list just in case it's corrupt
+            Path::deleteCacheFile("gamecontrollerdb.txt");
         }
     }
     else {