mypy

0a8d4254 - Fix spurious unreachable and disallow-any errors from deferred passes (#13575)

Fix spurious unreachable and disallow-any errors from deferred passes (#13575) This diff: - Fixes #8129 - Fixes #13043 - Fixes #13167 For more concise repros of these various issues, see the modified test files. But in short, there were two broad categories of errors: 1. Within the deferred pass, we tend to infer 'Any' for the types of different variables instead of the actual type. This interacts badly with our unreachable and disallow-any checks and causes spurious errors. Arguably, the better way of handling this error is to only collect errors during the final pass. I briefly experimented with this approach, but was unable to find a clean, efficient, and non-disruptive way of implementing this. So, I settled for sprinkling in a few more `not self.current_node_deferred` checks. 2. The `self.msg.disallowed_any_type(...)` call is normally guarded behind a `not self.chk.current_node_deferred` check. However, we were bypassing this check for `except` block assignments because we were deliberately setting that flag to False to work around some bug. For more context, see #2290. It appears we no longer need this patch anymore. I'm not entirely sure why, but I'm guessing we tightened and fixed the underlying problem with deferred passes some time during the past half-decade.