Fix null pointer exception in play button method

When the play queue was null, and this method was called a null pointer
exception would be thrown. This change adds an additional check to see
if the play queue is not null before making additional changes.

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

@@ -1069,12 +1069,17 @@ public int getOverrideResolutionIndex(final List<VideoStream> sortedVideos,
         // States
         //////////////////////////////////////////////////////////////////////////*/
 
-    private void animatePlayButtons(final boolean show, final int duration) {
+    private void animatePlayButtons(boolean show, final int duration) {
         animateView(playPauseButton, AnimationUtils.Type.SCALE_AND_ALPHA, show, duration);
-        if (playQueue.getIndex() > 0 || !show) {
+
+        if (playQueue == null) {
+            show = false;
+        }
+
+        if (!show || playQueue.getIndex() > 0) {
             animateView(playPreviousButton, AnimationUtils.Type.SCALE_AND_ALPHA, show, duration);
         }
-        if (playQueue.getIndex() + 1 < playQueue.getStreams().size() || !show) {
+        if (!show || playQueue.getIndex() + 1 < playQueue.getStreams().size()) {
             animateView(playNextButton, AnimationUtils.Type.SCALE_AND_ALPHA, show, duration);
         }