Proposing a minor change which should benefit type hinting.

[matmaer]

In message_pump.py, the TYPE_CHECKING branch defines:

app = getters.app(App)

But the else branch (the actual runtime property) declares:

def app(self) -> "App[object]":

This causes a "partially unknown type" warning on every self.app access in my dev env.

The fix is a one-line change to make both branches consistent:

app = getters.app(App[object])

I believe this should have zero runtime impact.

I have a PR ready if this looks reasonable, please let me know so I can add the link to the discussion in the PR, as the template instructs me to include a link. I didn't want to open an issue as it's purely about type hinting.

[matmaer]

Sorry, forgot to include the link to the commit main...matmaer:textual:fix/message-pump-app-unknown-type