Puppeteer for Firefox: wait for Firefox to close in case of a failure in the launcher

[ggrossetie]

Steps to reproduce

Tell us about your environment:

• Puppeteer version: 0.4.2 (puppeteer-firefox)
• Platform / OS version: Ubuntu 18.04.1 LTS
• Node.js version: v10.14.1

What steps will reproduce the problem?

1. Execute await puppeteer.launch({dumpio: true}) on Ubuntu Trusty (Travis)
2. The following trace can be seen in the console:

Failed to launch Firefox!
    at onClose (/home/travis/build/Mogztter/puppeteer-firefox-travis/node_modules/puppeteer-firefox/lib/firefox/Launcher.js:174:14)
    at Interface.helper.addEventListener (/home/travis/build/Mogztter/puppeteer-firefox-travis/node_modules/puppeteer-firefox/lib/firefox/Launcher.js:163:50)
    at Interface.emit (events.js:187:15)
    at Interface.close (readline.js:379:8)
    at Socket.onend (readline.js:157:10)
    at Socket.emit (events.js:187:15)
    at endReadableNT (_stream_readable.js:1094:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)

Please note that the root cause is not printed.

What is the expected result?

The root cause should be printed in the console since we are using dumpio (ie. why Firefox failed to launch).

What happens instead?

The Firefox process does not trigger the event exit because when Firefox failed to launch, the exception is catch and the process is killed using killFirefox:

https://github.com/GoogleChrome/puppeteer/blob/8aaca4eb1ed4020c56d03e3957c1e64e9a0e8b45/experimental/puppeteer-firefox/lib/firefox/Launcher.js#L125-L128

Basically the error message is lost because the process is killed immediately (ie. the process does not have time to exit gracefully).
I think we should use waitForFirefoxToClose promise to give the process a chance to exit gracefully (within a timeout) and only after force kill the process if the process is still not closed:

https://github.com/GoogleChrome/puppeteer/blob/8aaca4eb1ed4020c56d03e3957c1e64e9a0e8b45/experimental/puppeteer-firefox/lib/firefox/Launcher.js#L92-L104

[mjzffr]

Thanks for the report. I'm closing this issue since the experimental puppeteer-firefox package is no longer maintained. A replacement will be available
later this year. You can learn more about Mozilla's work on this at https://wiki.mozilla.org/Remote

See also #5137