fs: check initialized flag and exit if false in FSWatcher onchange

[BeniCheni]

After checking out the TODO comment in lib/internal/fs/watchers.js, this PR follows the suggestion to check initialized flag, and exits when "falsy", in favor to avoid firing events after the handle is closed.

node/lib/internal/fs/watchers.js

Lines 113 to 116 in e334002

	// TODO(joyeecheung): we may check self._handle.initialized here
	// and return if that is false. This allows us to avoid firing the event
	// after the handle is closed, and to fire both UV_RENAME and UV_CHANGE
	// if they are set by libuv at the same time.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[joyeecheung]

I don't really remember the context about this TODO anymore..could you add a test?

[BridgeAR]

Ping @BeniCheni

[BeniCheni]

@BridgeAR, sorry about the delay & thanks for pinging. Been learning how to write a test with the fs initialized flag. Haven’t figured out yet.

Any existing test that I could shadow? (Could use some mentoring. If no example, and I couldn’t figure, I will close this trivial PR to avoid any confusion. Thanks)

[BeniCheni]

Closing this PR for now, until when I figure out how to test with the initialized flag. Thanks for the previous review.