Skip movies/shows that don't have imdbIDs

With some explorer that might be the case and it won't work properly

backend/external_medias/external_medias.go

@@ -53,6 +53,9 @@ func GetMediaIDs(env *web.Env, mediaType string, source string, category string)
 		}
 		// Add them in the list of ids
 		for _, media := range medias {
+			if media.ImdbID == "" {
+				continue
+			}
 			ids = append(ids, media.ImdbID)
 		}
 	} else {
@@ -63,6 +66,9 @@ func GetMediaIDs(env *web.Env, mediaType string, source string, category string)
 		}
 		// Add them in the list of ids
 		for _, media := range medias {
+			if media.ImdbID == "" {
+				continue
+			}
 			ids = append(ids, media.ImdbID)
 		}
 	}