Fix NPE when mediaserver dies

Bug: 7497887
Change-Id: I92a1f332965da9462e2a063f2c1304a37a569384
diff --git a/src/com/android/music/MediaPlaybackService.java b/src/com/android/music/MediaPlaybackService.java
index 6414eb4..0009b53 100644
--- a/src/com/android/music/MediaPlaybackService.java
+++ b/src/com/android/music/MediaPlaybackService.java
@@ -1212,7 +1212,7 @@
     }
 
     private void stop(boolean remove_status_icon) {
-        if (mPlayer.isInitialized()) {
+        if (mPlayer != null && mPlayer.isInitialized()) {
             mPlayer.stop();
         }
         mFileToPlay = null;