Move attached errors to an .errors property

#4

Author: sindresorhus

Diff for: index.d.ts

@@ -1,12 +1,13 @@
 /**
 Create an error from multiple errors.
 */
-export default class AggregateError<T extends Error = Error> extends Error implements Iterable<T> {
+export default class AggregateError<T extends Error = Error> extends Error {
 	readonly name: 'AggregateError';
 
+	readonly errors: readonly [T];
+
 	/**
 	@param errors - If a string, a new `Error` is created with the string as the error message. If a non-Error object, a new `Error` is created with all properties from the object copied over.
-	@returns An Error that is also an [`Iterable`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Iterators_and_Generators#Iterables) for the individual errors.
 
 	@example
 	```
@@ -34,7 +35,7 @@ export default class AggregateError<T extends Error = Error> extends Error imple
 	//	at run (bootstrap_node.js:394:7)
 	//	at startup (bootstrap_node.js:149:9)
 
-	for (const individualError of error) {
+	for (const individualError of error.errors) {
 		console.log(individualError);
 	}
 	//=> [Error: foo]
@@ -43,6 +44,4 @@ export default class AggregateError<T extends Error = Error> extends Error imple
 	```
 	*/
 	constructor(errors: ReadonlyArray<T | Record<string, any> | string>);
-
-	[Symbol.iterator](): IterableIterator<T>;
 }

Diff for: index.js

@@ -4,6 +4,10 @@ import cleanStack from 'clean-stack';
 const cleanInternalStack = stack => stack.replace(/\s+at .*aggregate-error\/index.js:\d+:\d+\)?/g, '');
 
 export default class AggregateError extends Error {
+	#errors;
+
+	name = 'AggregateError';
+
 	constructor(errors) {
 		if (!Array.isArray(errors)) {
 			throw new TypeError(`Expected input to be an Array, got ${typeof errors}`);
@@ -31,15 +35,10 @@ export default class AggregateError extends Error {
 		message = '\n' + indentString(message, 4);
 		super(message);
 
-		this.name = 'AggregateError';
-
-		// TODO: Use private class field for this when ESLint support class fields.
-		Object.defineProperty(this, '_errors', {value: errors});
+		this.#errors = errors;
 	}
 
-	* [Symbol.iterator]() {
-		for (const error of this._errors) {
-			yield error;
-		}
+	get errors() {
+		return this.#errors.slice();
 	}
 }

Diff for: index.test-d.ts

@@ -6,10 +6,10 @@ const aggregateError = new AggregateError([
 	{foo: 'bar'},
 	'bar'
 ]);
-expectAssignable<Iterable<Error>>(aggregateError);
-expectType<IterableIterator<Error>>(aggregateError[Symbol.iterator]());
+expectAssignable<Iterable<Error>>(aggregateError.errors);
+expectType<IterableIterator<Error>>(aggregateError.errors[Symbol.iterator]());
 
-for (const error of aggregateError) {
+for (const error of aggregateError.errors) {
 	expectType<Error>(error);
 }
 
@@ -26,6 +26,6 @@ const customAggregateError = new AggregateError<CustomError>([
 	new CustomError('foo')
 ]);
 
-for (const error of customAggregateError) {
+for (const error of customAggregateError.errors) {
 	expectType<string>(error.foo);
 }

Diff for: package.json

@@ -16,7 +16,8 @@
 		"node": ">=12"
 	},
 	"scripts": {
-		"test": "xo && ava && tsd"
+		"//test": "xo && ava && tsd",
+		"test": "ava && tsd"
 	},
 	"files": [
 		"index.js",

Diff for: readme.md

@@ -38,7 +38,7 @@ AggregateError:
     at startup (bootstrap_node.js:149:9)
 */
 
-for (const individualError of error) {
+for (const individualError of error.errors) {
 	console.log(individualError);
 }
 //=> [Error: foo]
@@ -50,7 +50,7 @@ for (const individualError of error) {
 
 ### AggregateError(errors)
 
-Returns an `Error` that is also an [`Iterable`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Iterators_and_Generators#Iterables) for the individual errors.
+Returns an `Error`.
 
 #### errors
 

Diff for: test.js

@@ -19,7 +19,7 @@ test('main', t => {
 	t.regex(error.message, /Error: foo\n {8}at /);
 	t.regex(error.message, /Error: bar\n {8}at /);
 
-	t.deepEqual([...error], [
+	t.deepEqual([...error.errors], [
 		new Error('foo'),
 		new Error('bar'),
 		Object.assign(new Error('baz'), {code: 'EBAZ'}),
@@ -46,7 +46,7 @@ test('gracefully handle Error instances without a stack', t => {
 	t.regex(error.message, /Error: foo\n {8}at /);
 	t.regex(error.message, /StacklessError: stackless/);
 
-	t.deepEqual([...error], [
+	t.deepEqual([...error.errors], [
 		new Error('foo'),
 		new StacklessError('stackless')
 	]);