Fix it sometimes looping instead of going to next video when autoskipping at the end for playlists

Fix #1804

src/utils/pageUtils.ts

@@ -93,4 +93,8 @@ export function getExistingChapters(currentVideoID: VideoID, duration: number):
     }
 
     return chapters;
+}
+
+export function isPlayingPlaylist() {
+    return !!document.URL.includes("&list=");
 }