NodeJs 12: UnhandledPromiseRejectionWarning.

Steps to reproduce

Tell us about your environment:

• Puppeteer version: 2.0.0
• Platform / OS version: macOs 10.15.2
• URLs (if applicable):
• Node.js version: 12.4

What steps will reproduce the problem?

Code:

const puppeteer = require('puppeteer');

const main = async () => {
    const functionWithPagesInvocation = async (browser) => {
        const pages = await browser.pages();
        if (pages.length > 1) return pages[0].bringToFront();
    };
    const pool = [];
    for (let i = 0; i <= 5; i++) {
        const browser = await puppeteer.launch({ headless: true });
        pool.push(browser);

        await browser.newPage();
        functionWithPagesInvocation(browser).catch(e => console.error('Should catch error', e));
    }

    await Promise.all(pool.map(browser => browser.close()));
};

main().catch(e => console.error('Should atleast catch here', e));

Logs:

Should catch error Error: WebSocket is not open: readyState 2 (CLOSING)
    at WebSocket.send (/Users/petr/apify/puppeteer-testing/node_modules/ws/lib/websocket.js:329:19)
    at WebSocketTransport.send (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/WebSocketTransport.js:60:14)
    at Connection._rawSend (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Connection.js:86:21)
    at CDPSession.send (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Connection.js:181:33)
    at Page._initialize (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Page.js:137:20)
    at Function.create (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Page.js:48:16)
    at /Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Target.js:74:32
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
    at async Promise.all (index 0)
    at async BrowserContext.pages (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:311:19)
  -- ASYNC --
    at Target.<anonymous> (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/helper.js:111:15)
    at /Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:314:35
    at Array.map (<anonymous>)
    at BrowserContext.pages (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:314:14)
    at BrowserContext.<anonymous> (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/helper.js:112:23)
    at /Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:233:90
    at Array.map (<anonymous>)
    at Browser.pages (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:233:67)
    at Browser.<anonymous> (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/helper.js:112:23)
    at functionWithPagesInvocation (/Users/petr/apify/puppeteer-testing/main.js:5:37)
  -- ASYNC --
    at BrowserContext.<anonymous> (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/helper.js:111:15)
    at /Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:233:90
    at Array.map (<anonymous>)
    at Browser.pages (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:233:67)
    at Browser.<anonymous> (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/helper.js:112:23)
    at functionWithPagesInvocation (/Users/petr/apify/puppeteer-testing/main.js:5:37)
    at main (/Users/petr/apify/puppeteer-testing/main.js:14:9)
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
(node:29769) UnhandledPromiseRejectionWarning: Error: Protocol error (Page.enable): Target closed.
    at /Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Connection.js:183:56
    at new Promise (<anonymous>)
    at CDPSession.send (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Connection.js:182:12)
    at FrameManager.initialize (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/FrameManager.js:60:20)
    at Page._initialize (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Page.js:136:26)
    at Function.create (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Page.js:48:16)
    at /Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Target.js:74:32
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
    at async Promise.all (index 0)
    at async BrowserContext.pages (/Users/petr/apify/puppeteer-testing/node_modules/puppeteer/lib/Browser.js:311:19)
(node:29769) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)
(node:29769) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

What is the expected result? I would expect the exception to be handled.

What happens instead? I guess that due to the promise handling changes in node v11+ some promise inside puppeteer is rejected earlier than the error handler is attached, so the UnhandledPromiseRejectionWarning appears.

NOTE: It does not happen in NodeJs 10

[stale[bot]]

We’re marking this issue as unconfirmed because it has not had recent activity and we weren’t able to confirm it yet. It will be closed if no further activity occurs within the next 30 days.

[stale[bot]]

We are closing this issue. If the issue still persists in the latest version of Puppeteer, please reopen the issue and update the description. We will try our best to accomodate it!