RawAutocomplete's OverlayPortalController.hide() was called twice:
once when focus left the To field and again when ComposeScreen was popped,
triggering the _zOrderIndex assertion in overlay.dart.
Fix by:
1. pump() after entering the To field so the overlay has a frame to close
before the Subject field takes focus.
2. unfocus() + pump() before tapping Send so the overlay is already hidden
when the screen pops, preventing a second hide() on unmount.
Remove the _zOrderIndex string-filter from FlutterError.onError — the
root cause is fixed rather than suppressed.
Fixes#79
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
