Ensure compatibility with Node.js 10 and 12 (Fix missed one)

[lambdalisue]

Continuing from #30:
It seems that one fs.close() line still remains.

In my case, commit 4d6eafec caused denoland/deno#30718, so this PR should fix it and may also help users affected by that issue on Deno.

[lovell]

Thank you very much for the PR, and apologies for not noticing this usage when reviewing #30

I'd like to clarify that this package did not cause a problem in Deno, merely exposed that it had not yet fully implemented the Node.js fs.close() method as documented. To be fair to Deno, that API has been on quite a journey, as described in #30 (comment), so it doesn't surprise me.

[lambdalisue]

Thank you very much — this was really helpful!

Of course, considering the complexity of Node’s evolving specifications, I think it’s understandable that issues like this can happen (especially since this is a Node library, and Deno-related matters are technically out of scope).

Once this change is released in a patch, at least the applications I maintain will automatically be fixed, so I truly appreciate it.

[lovell]

v2.1.2 now available, thank you.