* fix(ibus): keep engine teardown correct when parent destroy fails
`do_destroy` passed `super().do_destroy` to `_handle_engine_destroy`.
PyGObject binds that vfunc to the GType rather than to the instance, so
calling it with no arguments raises:
TypeError: IBus.Object.destroy() takes exactly 1 argument (0 given)
This fired on every engine teardown. The exception escaped
`_handle_engine_destroy` before its return, so neither
`_active_instance = ...` nor `_focus_event.clear()` in the caller ran,
leaving a destroyed engine registered as active with focus still set --
the two values `_ibus_ping_status` (#523) reads to decide commit
readiness.
Two changes:
- Bind the parent destroy to the instance, falling back to
`IBus.Object.destroy(self)` only when the no-arg call raises TypeError,
so this keeps working if PyGObject binds the vfunc correctly later.
- Guard the parent destroy call so no failure there can skip teardown.
Fixes#606
* refactor(ibus): extract parent-destroy workaround into a testable helper
Codecov flagged the new code as uncovered (36% patch, below the 80%
target). The whole `if IBUS_AVAILABLE:` branch of `do_destroy` is
unreachable from the suite, which only ever exercises that method with
IBUS_AVAILABLE False -- the single line it replaced was already
uncovered on main for the same reason.
Move the workaround into a module-level `_invoke_parent_destroy`, the
same pattern `_handle_engine_destroy` already uses to make `do_destroy`
testable, and bind it with functools.partial at the call site.
Behaviour is unchanged. Coverage of the branch goes from 0 to all but
the one-line partial, and three tests now pin the actual contract:
pass-through when the binding is correct, retry with the instance on the
GType-binding TypeError, and no masking of other exceptions.
