"Resolve unsoundness caught by pytype --strict-none-binding.

See go/pytype-releases#strict-none-binding and go/pytype-smarter-optional. In
short, pytype was previously more permissive when variables were initialized to
None but may have been re-assigned later. This change improves pytype's ability
to catch unsoundness in the affected files.

PiperOrigin-RevId: 567951095

android_env/components/coordinator.py

@@ -92,7 +92,7 @@ def __init__(
     self._tmp_dir = tmp_dir or tempfile.gettempdir()
     self._orientation = np.zeros(4, dtype=np.uint8)
     self._interaction_rate_sec = interaction_rate_sec
-    self._interaction_thread = None
+    self._interaction_thread: InteractionThread | None = None
 
     # The size of the device screen in pixels (H x W).
     self._screen_size = np.array([0, 0], dtype=np.int32)
@@ -362,6 +362,7 @@ def _gather_simulator_signals(self) -> dict[str, np.ndarray]:
 
     # Grab pixels.
     if self._interaction_rate_sec > 0:
+      assert self._interaction_thread is not None
       pixels = self._interaction_thread.screenshot()  # Async mode.
     else:
       pixels = self._simulator.get_screenshot()  # Sync mode.