Clear up Highlight sound settings (#4194)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>
Closes https://github.com/Chatterino/chatterino2/issues/1540

src/messages/SharedMessageBuilder.cpp

@@ -19,14 +19,17 @@ namespace chatterino {
 
 namespace {
 
+    /**
+     * Gets the default sound url if the user set one,
+     * or the chatterino default ping sound if no url is set.
+     */
     QUrl getFallbackHighlightSound()
     {
         QString path = getSettings()->pathHighlightSound;
-        bool fileExists = QFileInfo::exists(path) && QFileInfo(path).isFile();
+        bool fileExists = !path.isEmpty() && QFileInfo::exists(path) &&
+                          QFileInfo(path).isFile();
 
-        // Use fallback sound when checkbox is not checked
-        // or custom file doesn't exist
-        if (getSettings()->customHighlightSound && fileExists)
+        if (fileExists)
         {
             return QUrl::fromLocalFile(path);
         }