Add null pointer check to getStopped

PackageSetting is not guaranteed to be non-null which caused test
failures. This adds a null check.

Bug: 184936704
Test: presubmit
Change-Id: Ie58ffa0d9abde5417e4db48389e526eaf43e0cf6

services/core/java/com/android/server/pm/PackageManagerService.java

@@ -23444,7 +23444,7 @@ public class PackageManagerService extends IPackageManager.Stub
         // writer
         synchronized (mLock) {
             final PackageSetting ps = mSettings.getPackageLPr(packageName);
-            if (ps.getStopped(userId) && !stopped) {
+            if (ps != null && ps.getStopped(userId) && !stopped) {
                 shouldUnhibernate = true;
             }
             if (!shouldFilterApplicationLocked(ps, callingUid, userId)