code: function onExit () {
        if (!responded) {
          errState = true;
          responded = true;
          error = new Error('Error spawning drone');
          error.blame = {
            type: 'user',
            message: 'Script prematurely exited'
          }
          error.stdout = stdout.join('\n');
          error.stderr = stderr.join('\n');
          callback(error);
  
          //
          // Remove listeners to related events.
          //
          drone.removeListener('error', onError);
          drone.removeListener('message', onCarapacePort);
          clearTimeout(timeout);
        }
      }
docs: If the drone exits prematurely then respond with an error containing the data we receieved from `stderr`