Merge pull request #1209 from GetStream/fix/null-map-values

fix(llc): handle user extra data name null condition

packages/stream_chat/lib/src/core/models/user.dart

@@ -82,7 +82,7 @@ class User extends Equatable {
   /// {@macro name}
   @JsonKey(ignore: true)
   String get name {
-    if (extraData.containsKey('name')) {
+    if (extraData.containsKey('name') && extraData['name'] != null) {
       final name = extraData['name']! as String;
       if (name.isNotEmpty) return name;
     }