Fix unhandled exception when lookup returns invalid IP early

Fixes #1737

source/core/index.ts

@@ -1101,11 +1101,21 @@ export default class Request extends Duplex implements RequestEvents<Request> {
 		const fn = options.cache ? this._createCacheableRequest : request;
 
 		try {
-			let requestOrResponse = await fn(url, this._requestOptions);
+			// We can't do `await fn(...)`,
+			// because stream `error` event can be emitted before `Promise.resolve()`.
+			let requestOrResponse = fn(url, this._requestOptions);
+
+			if (is.promise(requestOrResponse)) {
+				requestOrResponse = await requestOrResponse;
+			}
 
 			// Fallback
 			if (is.undefined(requestOrResponse)) {
-				requestOrResponse = await options.getFallbackRequestFunction()(url, this._requestOptions);
+				requestOrResponse = options.getFallbackRequestFunction()(url, this._requestOptions);
+
+				if (is.promise(requestOrResponse)) {
+					requestOrResponse = await requestOrResponse;
+				}
 			}
 
 			if (isClientRequest(requestOrResponse!)) {

test/http.ts

@@ -357,3 +357,15 @@ test('JSON request custom stringifier', withServer, async (t, server, got) => {
 		json: payload,
 	})).body, customStringify(payload));
 });
+
+test('ClientRequest can throw before promise resolves', async t => {
+	await t.throwsAsync(got('http://example.com', {
+		dnsLookup: ((_hostname: string, _options: unknown, callback: Function) => {
+			queueMicrotask(() => {
+				callback(null, 'fe80::0000:0000:0000:0000', 6);
+			});
+		}) as any
+	}), {
+		code: 'EINVAL'
+	});
+});