Fix unref'ing the timer in some environments

[nodkz]

It very strange but in some cases thrown "Error: interval.unref is not a function" in 5.1.0.

Error is thrown in line 56:

get-port/index.js

Lines 50 to 57 in 0edd17a

	if (interval === undefined) {
	interval = setInterval(() => {
	lockedPorts.old = lockedPorts.young;
	lockedPorts.young = new Set();
	}, releaseOldLockedPortsIntervalMs);
	interval.unref();
	}

If we change code to
if(interval.unref) interval.unref();

Then the error disappears.

[nodkz]

I found the root of the problem - it's Jest:
jestjs/jest#9033

It should be used with jest-environment-node and not the default jsdom env.

[sindresorhus]

You cannot assume the problem is Jest. Electron in render mode also doesn't have .unref. I think it would be best to just guard it without a message.

[nodkz]

Agreed 👍

It's ready for squashing.