Check for null in getDeviceOwnerOrProfileOwnerPackage

This prevents a system crash when running SessionTest on secondary
users.

bug: 138118013
bug: 138120084
Test: cts-tradefed run cts-dev -m CtsPackageInstallTestCases -t android.packageinstaller.install.cts.SessionTest
and cts-tradefed run cts-dev -m CtsPermission2TestCases -t android.permission2.cts.RestrictedPermissionsTest#onSideLoadRestrictedPermissionsWhitelistingDefault
Change-Id: I2be4d3121666c107aaf32113f7c13a9b5b3ff5dd
diff --git a/services/core/java/com/android/server/pm/ProtectedPackages.java b/services/core/java/com/android/server/pm/ProtectedPackages.java
index a374e14..231168e 100644
--- a/services/core/java/com/android/server/pm/ProtectedPackages.java
+++ b/services/core/java/com/android/server/pm/ProtectedPackages.java
@@ -92,6 +92,9 @@
         if (mDeviceOwnerUserId == userId) {
             return mDeviceOwnerPackage;
         }
+        if (mProfileOwnerPackages == null) {
+            return null;
+        }
         return mProfileOwnerPackages.get(userId);
     }