migrate to nnbd

Signed-off-by: Sahil Kumar <[email protected]>

packages/stream_chat/lib/src/api/channel.dart

@@ -620,7 +620,7 @@ class Channel {
   Future<SendReactionResponse> sendReaction(
     Message message,
     String type, {
-    Map<String, dynamic> extraData = const {},
+    Map<String, Object> extraData = const {},
     bool enforceUnique = false,
   }) async {
     _checkInitialized();

packages/stream_chat/lib/src/api/responses.dart

@@ -209,7 +209,7 @@ class GetMessageResponse extends _BaseResponse {
     final res = _$GetMessageResponseFromJson(json);
     final jsonChannel = res.message.extraData.remove('channel');
     if (jsonChannel != null) {
-      res.channel = ChannelModel.fromJson(jsonChannel);
+      res.channel = ChannelModel.fromJson(jsonChannel as Map<String, dynamic>);
     }
     return res;
   }