fix(ui): Only show stickers that are images

lib/shared/models/sticker.dart

@@ -85,4 +85,7 @@ class Sticker with _$Sticker {
       .toList(),
     suggests,
   );
+
+  /// True, if the sticker is backed by an image with MIME type image/*.
+  bool get isImage => mediaType.startsWith('image/');
 }

lib/ui/bloc/addcontact_bloc.dart

@@ -54,6 +54,7 @@ class AddContactBloc extends Bloc<AddContactEvent, AddContactState> {
       }
     }
 
+    assert(result.conversation != null, 'RequestedConversationEvent must contain a not null conversation');
     GetIt.I.get<ConversationBloc>().add(
       RequestedConversationEvent(
         result.conversation!.jid,

lib/ui/bloc/stickers_bloc.dart

@@ -31,6 +31,8 @@ class StickersBloc extends Bloc<StickersEvent, StickersState> {
     final map = <StickerKey, Sticker>{};
     for (final pack in event.stickerPacks) {
       for (final sticker in pack.stickers) {
+        if (!sticker.isImage) continue;
+
         map[StickerKey(pack.id, sticker.hashKey)] = sticker;
       }
     }
@@ -92,6 +94,8 @@ class StickersBloc extends Bloc<StickersEvent, StickersState> {
     if (result is StickerPackImportSuccessEvent) {
       final sm = Map<StickerKey, Sticker>.from(state.stickerMap);
       for (final sticker in result.stickerPack.stickers) {
+        if (!sticker.isImage) continue;
+
         sm[StickerKey(result.stickerPack.id, sticker.hashKey)] = sticker;
       }
       emit(
@@ -128,6 +132,8 @@ class StickersBloc extends Bloc<StickersEvent, StickersState> {
   Future<void> _onStickerPackAdded(StickerPackAddedEvent event, Emitter<StickersState> emit) async {
     final sm = Map<StickerKey, Sticker>.from(state.stickerMap);
     for (final sticker in event.stickerPack.stickers) {
+      if (!sticker.isImage) continue;
+
       sm[StickerKey(event.stickerPack.id, sticker.hashKey)] = sticker;
     }