Dont cache integrations that are not found (#23316)

Author: balloob

homeassistant/loader.py

@@ -161,11 +161,13 @@ async def async_get_integration(hass: 'HomeAssistant', domain: str)\
         await int_or_evt.wait()
         int_or_evt = cache.get(domain, _UNDEF)
 
-    if int_or_evt is _UNDEF:
-        pass
-    elif int_or_evt is None:
-        raise IntegrationNotFound(domain)
-    else:
+        # When we have waited and it's _UNDEF, it doesn't exist
+        # We don't cache that it doesn't exist, or else people can't fix it
+        # and then restart, because their config will never be valid.
+        if int_or_evt is _UNDEF:
+            raise IntegrationNotFound(domain)
+
+    if int_or_evt is not _UNDEF:
         return cast(Integration, int_or_evt)
 
     event = cache[domain] = asyncio.Event()
@@ -197,7 +199,12 @@ async def async_get_integration(hass: 'HomeAssistant', domain: str)\
         return integration
 
     integration = Integration.resolve_legacy(hass, domain)
-    cache[domain] = integration
+    if integration is not None:
+        cache[domain] = integration
+    else:
+        # Remove event from cache.
+        cache.pop(domain)
+
     event.set()
 
     if not integration: