Fix time trigger crash when using entity_id dict format without offset (#171006)

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

homeassistant/components/homeassistant/triggers/time.py

@@ -268,9 +268,9 @@ async def async_attach_trigger(  # noqa: C901
             # entity
             update_entity_trigger(at_time, new_state=hass.states.get(at_time))
             to_track.append(TrackEntity(at_time, update_entity_trigger_event))
-        elif isinstance(at_time, dict) and CONF_OFFSET in at_time:
-            # entity with offset
-            entity_id: str = at_time.get(CONF_ENTITY_ID, "")
+        elif isinstance(at_time, dict):
+            # entity with optional offset
+            entity_id: str = at_time[CONF_ENTITY_ID]
             offset: timedelta = at_time.get(CONF_OFFSET, timedelta(0))
             update_entity_trigger(
                 entity_id, new_state=hass.states.get(entity_id), offset=offset

tests/components/homeassistant/triggers/test_time.py

@@ -732,6 +732,52 @@ async def test_if_fires_using_at_sensor_with_offset(
     )
 
 
+async def test_if_fires_using_at_sensor_dict_without_offset(
+    hass: HomeAssistant,
+    freezer: FrozenDateTimeFactory,
+    service_calls: list[ServiceCall],
+) -> None:
+    """Test for firing at sensor time using dict format without offset."""
+    now = dt_util.now()
+
+    trigger_dt = now.replace(hour=5, minute=0, second=0, microsecond=0) + timedelta(2)
+
+    hass.states.async_set(
+        "sensor.next_alarm",
+        trigger_dt.isoformat(),
+        {ATTR_DEVICE_CLASS: SensorDeviceClass.TIMESTAMP},
+    )
+
+    time_that_will_not_match_right_away = trigger_dt - timedelta(minutes=1)
+
+    freezer.move_to(dt_util.as_utc(time_that_will_not_match_right_away))
+    assert await async_setup_component(
+        hass,
+        automation.DOMAIN,
+        {
+            automation.DOMAIN: {
+                "trigger": {
+                    "platform": "time",
+                    "at": {
+                        "entity_id": "sensor.next_alarm",
+                    },
+                },
+                "action": {
+                    "service": "test.automation",
+                    "data_template": {"some": "{{ trigger.entity_id }}"},
+                },
+            }
+        },
+    )
+    await hass.async_block_till_done()
+
+    async_fire_time_changed(hass, trigger_dt + timedelta(seconds=1))
+    await hass.async_block_till_done()
+
+    assert len(service_calls) == 1
+    assert service_calls[0].data["some"] == "sensor.next_alarm"
+
+
 @pytest.mark.parametrize(
     "conf",
     [