Merge pull request #1280 from Xefir/fix-npe-wallpaper-service

Fix NPE on Wallpaper Service

twidere.component.nyan/src/main/java/org/mariotaku/twidere/nyan/NyanWallpaperService.java

@@ -115,12 +115,14 @@ public class NyanWallpaperService extends WallpaperService implements NyanConsta
 
         private void updateHelperState() {
             final PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
+            if (pm != null) {
                 if (pm.isScreenOn()) {
                     mHelper.start();
                 } else {
                     mHelper.stop();
                 }
             }
+        }
 
         private void updateSurface() {
             if (mPreferences == null) return;