Fix unhandled errors if throwing in an async handler

Author: szmarczak

documentation/examples/gh-got.js

@@ -2,7 +2,7 @@
 const got = require('../..');
 const package = require('../../package');
 
-const getRateLimit = ({headers}) => ({
+const getRateLimit = (headers) => ({
 	limit: parseInt(headers['x-ratelimit-limit'], 10),
 	remaining: parseInt(headers['x-ratelimit-remaining'], 10),
 	reset: new Date(parseInt(headers['x-ratelimit-reset'], 10) * 1000)

documentation/lets-make-a-plugin.md

@@ -161,7 +161,7 @@ Umm... `response.headers['x-ratelimit-remaining']` doesn't look good. What about
 Yeah, definitely. Since `response.headers` is an object, we can easily parse these:
 
 ```js
-const getRateLimit = ({headers}) => ({
+const getRateLimit = (headers) => ({
 	limit: parseInt(headers['x-ratelimit-limit'], 10),
 	remaining: parseInt(headers['x-ratelimit-remaining'], 10),
 	reset: new Date(parseInt(headers['x-ratelimit-reset'], 10) * 1000)
@@ -182,7 +182,7 @@ getRateLimit({
 Let's integrate it:
 
 ```js
-const getRateLimit = ({headers}) => ({
+const getRateLimit = (headers) => ({
 	limit: parseInt(headers['x-ratelimit-limit'], 10),
 	remaining: parseInt(headers['x-ratelimit-remaining'], 10),
 	reset: new Date(parseInt(headers['x-ratelimit-reset'], 10) * 1000)

source/create.ts

@@ -113,9 +113,18 @@ const create = (defaults: Defaults): Got => {
 			return root;
 		});
 
-		if (result !== root && !options.isStream) {
-			Object.setPrototypeOf(result, Object.getPrototypeOf(root));
-			Object.defineProperties(result, Object.getOwnPropertyDescriptors(root));
+		if (result !== root && !options.isStream && root) {
+			const typedResult = result as Promise<unknown>;
+
+			const {then: promiseThen, catch: promiseCatch, finally: promiseFianlly} = typedResult;
+			Object.setPrototypeOf(typedResult, Object.getPrototypeOf(root));
+			Object.defineProperties(typedResult, Object.getOwnPropertyDescriptors(root));
+
+			// These should point to the new promise
+			// eslint-disable-next-line promise/prefer-await-to-then
+			typedResult.then = promiseThen;
+			typedResult.catch = promiseCatch;
+			typedResult.finally = promiseFianlly;
 		}
 
 		return result;

source/types.ts

@@ -8,7 +8,7 @@ import {URL} from 'url';
 import {Readable as ReadableStream} from 'stream';
 import {Timings, IncomingMessageWithTimings} from '@szmarczak/http-timer';
 import CacheableLookup from 'cacheable-lookup';
-import {Except, Merge, Promisable} from 'type-fest';
+import {Except, Merge} from 'type-fest';
 import {GotReturn} from './create';
 import {GotError, HTTPError, MaxRedirectsError, ParseError, TimeoutError, RequestError} from './errors';
 import {Hooks} from './known-hook-events';
@@ -77,7 +77,7 @@ export interface RetryObject {
 
 export type RetryFunction = (retryObject: RetryObject) => number;
 
-export type HandlerFunction = <T extends GotReturn>(options: NormalizedOptions, next: (options: NormalizedOptions) => T) => Promisable<T>;
+export type HandlerFunction = <T extends GotReturn>(options: NormalizedOptions, next: (options: NormalizedOptions) => T) => T | Promise<T>;
 
 export interface DefaultRetryOptions {
 	limit: number;

test/create.ts

@@ -296,3 +296,17 @@ test('async handlers', withServer, async (t, server, got) => {
 	// @ts-ignore Manual tests
 	t.true((await promise).modified);
 });
+
+test('async handlers can throw', async t => {
+	const message = 'meh';
+
+	const instance = got.extend({
+		handlers: [
+			async () => {
+				throw new Error(message);
+			}
+		]
+	});
+
+	await t.throwsAsync(instance('https://example.com'), {message});
+});