Fix startup race in cast (#113843)

homeassistant/components/cast/__init__.py

@@ -25,9 +25,9 @@ PLATFORMS = [Platform.MEDIA_PLAYER]
 
 async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
     """Set up Cast from a config entry."""
+    hass.data[DOMAIN] = {"cast_platform": {}, "unknown_models": {}}
     await home_assistant_cast.async_setup_ha_cast(hass, entry)
     await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
-    hass.data[DOMAIN] = {"cast_platform": {}, "unknown_models": {}}
     await async_process_integration_platforms(hass, DOMAIN, _register_cast_platform)
     return True