Fixed uncaught exceptions for demo (#34117)

tests/components/demo/test_init.py

@@ -29,6 +29,7 @@ def demo_cleanup(hass):
 async def test_setting_up_demo(hass):
     """Test if we can set up the demo and dump it to JSON."""
     assert await async_setup_component(hass, DOMAIN, {DOMAIN: {}})
+    await hass.async_block_till_done()
     await hass.async_start()
 
     # This is done to make sure entity components don't accidentally store

tests/ignore_uncaught_exceptions.py

@@ -1,6 +1,5 @@
 """List of modules that have uncaught exceptions today. Will be shrunk over time."""
 IGNORE_UNCAUGHT_EXCEPTIONS = [
-    ("tests.components.demo.test_init", "test_setting_up_demo"),
     ("tests.components.dyson.test_air_quality", "test_purecool_aiq_attributes"),
     ("tests.components.dyson.test_air_quality", "test_purecool_aiq_update_state"),
     (