simple-email/node_modules/aggregate-error/index.js

'use strict';
const indentString = require('indent-string');
const cleanStack = require('clean-stack');

const cleanInternalStack = stack => stack.replace(/\s+at .*aggregate-error\/index.js:\d+:\d+\)?/g, '');

class AggregateError extends Error {
	constructor(errors) {
		// Even though strings are iterable, we don't allow them to prevent subtle user mistakes
		if (!errors[Symbol.iterator] || typeof errors === 'string') {
			throw new TypeError(`Expected input to be iterable, got ${typeof errors}`);
		}

		errors = Array.from(errors).map(err => err instanceof Error ? err : new Error(err));

		let message = errors.map(err => cleanInternalStack(cleanStack(err.stack))).join('\n');
		message = '\n' + indentString(message, 4);

		super(message);
		this.name = this.constructor.name;
		Object.defineProperty(this, '_errors', {value: errors});
	}
	* [Symbol.iterator]() {
		for (const error of this._errors) {
			yield error;
		}
	}
}

module.exports = AggregateError;