code: function (execPlan, error, stderr, errorHandler) {
      var shouldContinue      = execPlan.continuesOnError(); // default to using configured policy
      var errorHandlerDefined = utils.isFunction(errorHandler);
      var errorHandlerReturn;
      var shouldOverridePolicy; // whether the given error handler is overriding the
                                // "continue on error" policy already set on the exec plan
      
      // determine whether the "continue on error" policy should be overridden by the given error
      // error handler. this is determined by whether the given error handler returns either true
      // or false. any other return, e.g., undefined, will signify that the policy should be used.
      if (errorHandlerDefined) errorHandlerReturn = errorHandler(error, stderr);
      shouldOverridePolicy = ((errorHandlerReturn === true) || (errorHandlerReturn === false));
      if (shouldOverridePolicy) {
          shouldContinue = errorHandlerReturn;
      } else {  // not overriding the policy has the side-effect of allowing 'execerror' to fire
          execPlan.emit('execerror', error, stderr);
      }
  
      return shouldContinue;
  }
docs: Provide a common handler for errors that occur during the execution of a plan.
  @param execPlan ExecPlan
  @param error Error
  @param stderr String
  @param errorHandler Function
  @param error Error
  @param stderr String
  @return Boolean - whether the plan should continue to execute