addToWatchlist raise NotFound exception for invalid media (#1401)

Author: JonnyWong16

plexapi/myplex.py

@@ -963,7 +963,9 @@ def addToWatchlist(self, items):
                     objects to be added to the watchlist.
 
             Raises:
-                :exc:`~plexapi.exceptions.BadRequest`: When trying to add invalid or existing
+                :exc:`~plexapi.exceptions.BadRequest`: When trying to add existing
+                    media to the watchlist.
+                :exc:`~plexapi.exceptions.NotFound`: When trying to add invalid
                     media to the watchlist.
         """
         if not isinstance(items, list):

tests/test_myplex.py

@@ -310,7 +310,7 @@ def test_myplex_watchlist(account, movie, show, artist):
         account.removeFromWatchlist(movie)
 
     # Test adding invalid item to watchlist
-    with pytest.raises(BadRequest):
+    with pytest.raises(NotFound):
         account.addToWatchlist(artist)