code: public RuntimeException traceError( RuntimeException cause, JsonReader reader ) {
          RuntimeException exception = traceError( cause );
          traceReaderInfo( reader );
          return exception;
      }
docs: Trace an error with current reader state and returns a corresponding exception.
  
  @param cause cause of the error
  @param reader current reader
  
  @return a {@link JsonDeserializationException} if we wrap the exceptions, the cause otherwise