какие то выкрутасы писькой

lib/core/protocol/packet.dart

@@ -55,7 +55,8 @@ class Packet {
 
 class PacketError implements Exception {
   final String message;
-  const PacketError(this.message);
+  final String? errorKey;
+  const PacketError(this.message, {this.errorKey});
   @override
   String toString() => message;
 }

lib/core/transport/dispatcher.dart

@@ -70,11 +70,14 @@ class PacketDispatcher {
 
       if (packet.isError) {
         final message = messageFromErrorPayload(packet.payload);
+        final errorKey = packet.payload is Map
+            ? packet.payload['error']?.toString()
+            : null;
         if (packet.payload is Map &&
             packet.payload['message'] == 'FAIL_LOGIN_TOKEN') {
           completer.completeError(SessionExpiredException(message));
         } else {
-          completer.completeError(PacketError(message));
+          completer.completeError(PacketError(message, errorKey: errorKey));
         }
       } else {
         completer.complete(packet);