Don't raise errors on failed ControllerApplication shutdown

Author: puddly

tests/test_application.py

@@ -1103,3 +1103,20 @@ def nvram_init(req):
     assert nvram[NwkNvIds.STARTUP_OPTION] == t.StartupOptions.ClearState.serialize()
     assert nvram[NwkNvIds.LOGICAL_TYPE] == t.DeviceLogicalType.Coordinator.serialize()
     assert nvram[NwkNvIds.ZDO_DIRECT_CB] == t.Bool(True).serialize()
+
+
+@pytest_mark_asyncio_timeout(seconds=3)
+async def test_clean_shutdown(application, mocker):
+    app, znp_server = application
+
+    # This should not throw
+    await app.shutdown()
+
+
+@pytest_mark_asyncio_timeout(seconds=3)
+async def test_unclean_shutdown(application, mocker):
+    app, znp_server = application
+    app._znp = None
+
+    # This should also not throw
+    await app.shutdown()

zigpy_znp/zigbee/application.py

@@ -216,7 +216,9 @@ async def shutdown(self):
         """Shutdown application."""
 
         self._reconnect_task.cancel()
-        self._znp.close()
+
+        if self._znp is not None:
+            self._znp.close()
 
     def _bind_callbacks(self, api):
         api.callback_for_response(