Make sure shutdown signals aren't trapped forever

[Tyler-Murphy]

Right now, it seems like this library is preventing the SIGINT (ctrl-C) signal from shutting down my project.

I made these changes using github's edit button, so I haven't tested/linted anything, and there could be mistakes. I have confirmed that making these changes causes SIGINT to shut down my project like I expect it to.

See this comment for an explanation: berstend/puppeteer-extra#467 (comment). Here are the comment's contents at the time of writing, in case the link stops working:

I've run into problems like this before, where a process.on listener traps SIGINT every time it's sent.

Reproduce the problem with this script. Run it and try hitting ctrl-C repeatedly. It'll be trapped every time and the process won't exit.

process.on(`SIGINT`, () => console.log(`caught SIGINT`))
setInterval(() => {}, 1e3) // do work to prevent immediate exit

I've fixed this a couple ways in the past.

1. Use process.once, and after cleanup work is complete, print a message saying something like "send SIGINT again to exit".
2. Re-emit the kill signal after cleanup work is complete.

Option 2 seems like a better fit in this case, and it works better in conjunction with other, unrelated cleanup scripts with their own SIGINT listeners. Here's what it looks like:

process.once(`SIGINT`, () => {
	console.log(`caught SIGINT`)
	process.kill(process.pid, `SIGINT`) // send `SIGINT` back to self
})
setInterval(() => {}, 1e3) // do work

I tried replacing the puppeteer-extra-plugin process.on listeners in the index file with process.once listeners as described, and it seems to fix the problem for me.

For example:

if (this.onClose) {
                if (opts.options.handleSIGINT !== false) {
                    process.once('SIGINT', () => {
                        this.onClose()
                        process.kill(process.pid, `SIGINT`)
                    });
                }
                ...

Note: I haven't tested this against the other test cases in this thread, but it solved my problem. Maybe others can see if it works for them, too.