Fix crash on unistalling app

Only update the battery info if the app exists.

Bug: 20918104
Change-Id: I61481be53cfc72d49868f14a940a09c83f7a5cc2

src/com/android/settings/applications/InstalledAppDetails.java

@@ -248,8 +248,10 @@ public class InstalledAppDetails extends AppInfoBase
         getLoaderManager().restartLoader(LOADER_CHART_DATA,
                 ChartDataLoader.buildArgs(NetworkTemplate.buildTemplateMobileWildcard(), app),
                 mDataCallbacks);
+        if (mPackageInfo != null) {
             new BatteryUpdater().execute();
         }
+    }
 
     @Override
     public void onPause() {