Handle null list from getPackagesForOps

                (AppOpsManager) mContext.getSystemService(Context.APP_OPS_SERVICE);

        List<AppOpsManager.PackageOps> appOps = aoManager.getPackagesForOps(LOCATION_OPS);

        final int appOpsCount = appOps != null ? appOps.size() : 0;

        // Process the AppOps list and generate a preference list.

        ArrayList<Request> requests = new ArrayList<>(appOps.size());

        ArrayList<Request> requests = new ArrayList<>(appOpsCount);

        final long now = System.currentTimeMillis();

        final UserManager um = (UserManager) mContext.getSystemService(Context.USER_SERVICE);

        final List<UserHandle> profiles = um.getUserProfiles();

        final int appOpsN = appOps.size();

        for (int i = 0; i < appOpsN; ++i) {

        for (int i = 0; i < appOpsCount; ++i) {

            AppOpsManager.PackageOps ops = appOps.get(i);

            // Don't show the Android System in the list - it's not actionable for the user.

            // Also don't show apps belonging to background users except managed users.