Fix sponsors not automatically skipping at 00:00

Author: the-blank-x

app/src/main/java/org/schabi/newpipe/player/Player.java

@@ -1680,7 +1680,7 @@ private void triggerProgressUpdate(final boolean isRewind) {
                 simpleExoPlayer.getBufferedPercentage()
         );
 
-        if (sponsorBlockMode == SponsorBlockMode.ENABLED) {
+        if (sponsorBlockMode == SponsorBlockMode.ENABLED && isPrepared) {
             final VideoSegment segment = getSkippableSegment(currentProgress);
             if (segment == null) {
                 lastSkipTarget = -1;