The previous code assumed that `initFrame` during the `new_frame` state would always result in the `in_frame` state, but that's not always the case. `initFrame` can also result in the `skippable_frame` state, which would lead to access of union field 'in_frame' while field 'skipping_frame' is active.

Now, the switch is re-entered with the updated state so either case is handled appropriately.

Fixes the crashes from https://github.com/ziglang/zig/issues/24817