fix: KeyWatcher.updates() returns type of Entry | None

[tekumara]

vscode/pyright infers the type of KeyWatcher.updates() as Unknown:

with this fix the type is now inferred as Entry | None:

in this example e could be None, so the type checker is now correctly telling us we haven't checked the None case (hence the red squiggly lines)

[wallyqs]

Thanks for the fix!