Remove impossible exception handling in youtube controller (#782)

* Remove impossible exception handling in youtube controller

* Remove unused import

pychromecast/controllers/youtube.py

@@ -8,7 +8,6 @@
 
 from . import BaseController
 from ..const import MESSAGE_TYPE
-from ..error import UnsupportedNamespace
 from ..config import APP_YOUTUBE
 
 YOUTUBE_NAMESPACE = "urn:x-cast:com.google.youtube.mdx"
@@ -83,11 +82,7 @@ def update_screen_id(self):
         (send message will launch app if it is not running).
         """
         self.status_update_event.clear()
-        # This gets the screenId but always throws. Couldn't find a better way.
-        try:
-            self.send_message({MESSAGE_TYPE: TYPE_GET_SCREEN_ID})
-        except UnsupportedNamespace:
-            pass
+        self.send_message({MESSAGE_TYPE: TYPE_GET_SCREEN_ID})
         status = self.status_update_event.wait(10)
         if not status:
             _LOGGER.warning("Failed to update screen_id")