API refactor to replace assert (#172862)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

homeassistant/components/api/__init__.py

@@ -222,7 +222,7 @@ class APIStatesView(HomeAssistantView):
             states = (
                 state.as_dict_json
                 for state in hass.states.async_all()
-                if entity_perm(state.entity_id, "read")
+                if entity_perm(state.entity_id, POLICY_READ)
             )
         response = web.Response(
             body=b"".join((b"[", b",".join(states), b"]")),
@@ -294,8 +294,10 @@ class APIEntityStateView(HomeAssistantView):
 
         # Read the state back for our response
         status_code = HTTPStatus.CREATED if is_new_state else HTTPStatus.OK
-        state = hass.states.get(entity_id)
-        assert state
+        if (state := hass.states.get(entity_id)) is None:
+            return self.json_message(
+                "Error storing state.", HTTPStatus.INTERNAL_SERVER_ERROR
+            )
         resp = self.json(state.as_dict(), status_code)
 
         resp.headers.add("Location", f"/api/states/{entity_id}")

tests/components/api/test_init.py

@@ -124,6 +124,18 @@ async def test_api_state_change_with_bad_state(
     assert resp.status == HTTPStatus.BAD_REQUEST
 
 
+async def test_api_state_change_internal_error(
+    hass: HomeAssistant, mock_api_client: TestClient
+) -> None:
+    """Test 500 is returned when state cannot be read back after being set."""
+    with patch.object(ha.StateMachine, "async_set"):
+        resp = await mock_api_client.post(
+            "/api/states/test.entity", json={"state": "on"}
+        )
+    assert resp.status == HTTPStatus.INTERNAL_SERVER_ERROR
+    assert await resp.json() == {"message": "Error storing state."}
+
+
 async def test_api_state_change_with_bad_data(
     hass: HomeAssistant, mock_api_client: TestClient
 ) -> None: