Fix lookup by Plex media key when playing on Sonos (#38119)

tests/components/plex/test_playback.py

@@ -1,4 +1,6 @@
 """Tests for Plex player playback methods/services."""
+from plexapi.exceptions import NotFound
+
 from homeassistant.components.media_player.const import (
     ATTR_MEDIA_CONTENT_ID,
     ATTR_MEDIA_CONTENT_TYPE,
@@ -52,7 +54,7 @@ async def test_sonos_playback(hass):
             True,
         )
 
-    # Test success with dict
+    # Test success with plex_key
     with patch.object(
         hass.components.sonos,
         "get_coordinator_name",
@@ -69,7 +71,7 @@ async def test_sonos_playback(hass):
             True,
         )
 
-    # Test success with plex_key
+    # Test success with dict
     with patch.object(
         hass.components.sonos,
         "get_coordinator_name",
@@ -86,6 +88,23 @@ async def test_sonos_playback(hass):
             True,
         )
 
+    # Test media lookup failure
+    with patch.object(
+        hass.components.sonos,
+        "get_coordinator_name",
+        return_value="media_player.sonos_kitchen",
+    ), patch.object(mock_plex_server, "fetchItem", side_effect=NotFound):
+        assert await hass.services.async_call(
+            DOMAIN,
+            SERVICE_PLAY_ON_SONOS,
+            {
+                ATTR_ENTITY_ID: "media_player.sonos_kitchen",
+                ATTR_MEDIA_CONTENT_TYPE: MEDIA_TYPE_MUSIC,
+                ATTR_MEDIA_CONTENT_ID: "999",
+            },
+            True,
+        )
+
     # Test invalid Plex server requested
     with patch.object(
         hass.components.sonos,