Bug 452962: Fix crash when Try clicked to stop audio alarm with fade

This implements a workaround for a Phonon crash where
~VolumeFaderEffect() called by ~MediaObject() crashes.

Changelog

 KAlarm Change Log
 
-=== Version 3.4.1 (KDE Gear 22.04.1) --- 20 April 2022 ===
+=== Version 3.4.1 (KDE Gear 22.04.1) --- 25 April 2022 ===
 * Fix checkboxes being disabled in Preferences dialogue.
 * Fix time spin boxes being displayed in the wrong position.
+* Fix crash when Try clicked to stop audio alarm with fade [KDE Bug 452962]
 
 === Version 3.4.0 (KDE Gear 22.04) --- 6 April 2022 ===
 * Allow calendars and date picker to be shown together in side panel [KDE Bug 440250]

src/messagedisplayhelper.cpp

@@ -982,6 +982,17 @@ AudioPlayer::AudioPlayer(const QString& audioFile, float volume, float fadeVolum
 AudioPlayer::~AudioPlayer()
 {
     qCDebug(KALARM_LOG) << "MessageDisplayHelper::~AudioPlayer";
+    // A bug in Phonon causes a crash when the VolumeFaderEffect is deleted due
+    // to being a child of MediaObject. This workaround prevents the crash by
+    // removing and deleting VolumeFaderEffect before ~MediaObject() is called.
+    const auto effects = mPath.effects();
+    for (Phonon::Effect* effect : effects)
+    {
+        mPath.removeEffect(effect);
+        delete effect;
+    }
+    // --- End of workaround for Phonon crash
+
     delete mAudioObject;
     mAudioObject = nullptr;
     // Notify after deleting mAudioPlayer, so that isAudioPlaying() will