We currently don't emit any errors in await xyz expressions if xyz is not awaitable. We should probably do something similar to what we do for iterators or context managers, where we emit helpful diagnostics if calls to respective dunder methods fail. For example:

class NotAwaitable: ...

class NotAwaitable2:
    # not async!
    def __await__(self):
        pass

async def main():
    x = await 1  # should be an error
    y = await NotAwaitable()  # should be an error
    z = await NotAwaitable2()  # should be an error

The entrypoint to implement this is here: https://github.com/astral-sh/ruff/blob/27b03a9d7bf779049585bb6cfbf229f18352572d/crates/ty_python_semantic/src/types.rs#L4868