Relax type annotation for DataUpdateCoordinator data (#49827)

homeassistant/helpers/update_coordinator.py

@@ -52,7 +52,12 @@ class DataUpdateCoordinator(Generic[T]):
         self.update_method = update_method
         self.update_interval = update_interval
 
-        self.data: T | None = None
+        # It's None before the first successful update.
+        # Components should call async_config_entry_first_refresh
+        # to make sure the first update was successful.
+        # Set type to just T to remove annoying checks that data is not None
+        # when it was already checked during setup.
+        self.data: T = None  # type: ignore[assignment]
 
         self._listeners: list[CALLBACK_TYPE] = []
         self._job = HassJob(self._handle_refresh_interval)
@@ -133,7 +138,7 @@ class DataUpdateCoordinator(Generic[T]):
         """
         await self._debounced_refresh.async_call()
 
-    async def _async_update_data(self) -> T | None:
+    async def _async_update_data(self) -> T:
         """Fetch the latest data from the source."""
         if self.update_method is None:
             raise NotImplementedError("Update method not implemented")