code: public static Throwable onOperatorError(Throwable error, Context context) {
  		return onOperatorError(null, error, context);
  	}
docs: Map an "operator" error. The
  result error will be passed via onError to the operator downstream after
  checking for fatal error via
  {@link Exceptions#throwIfFatal(Throwable)}.
  
  @param error the callback or operator error
  @param context a context that might hold a local error consumer
  @return mapped {@link Throwable}