message: fix debug_events_writer: avoid possible NULL pointer dereference
diff: @@ -306,7 +306,7 @@ void DebugEventsWriter::WriteSerializedExecutionDebugEvent(
  mu = &graph_execution_trace_buffer_mu_;
  break;
  default:
  - break;
  + return;
  }
  if (circular_buffer_size_ <= 0) {
  