🚑 Fix cannot load ongoing call

lib/models/call.dart

@@ -14,7 +14,8 @@ class Call {
   String externalId;
   int founderId;
   int channelId;
-  List<dynamic> participants;
+  @JsonKey(defaultValue: [])
+  List<dynamic>? participants;
   Channel channel;
 
   Call({

lib/models/call.g.dart

@@ -19,7 +19,7 @@ Call _$CallFromJson(Map<String, dynamic> json) => Call(
       externalId: json['external_id'] as String,
       founderId: (json['founder_id'] as num).toInt(),
       channelId: (json['channel_id'] as num).toInt(),
-      participants: json['participants'] as List<dynamic>,
+      participants: json['participants'] as List<dynamic>? ?? [],
       channel: Channel.fromJson(json['channel'] as Map<String, dynamic>),
     );