Bound TGS decoding and keep invalid icons out of animation

tools/chatgui/src/animtimer.cpp

@@ -20,6 +20,7 @@ void AnimTimer::shutdown() {
 }
 
 void AnimTimer::registerIcon(const QString &key, LottieIcon *icon) {
+    if (!icon || !icon->isValid()) { GUI_WARN("AnimTimer: invalid icon registration key=%s", qPrintable(key)); return; }
     m_icons.insert(key, icon);
 }