Adding a check if the user exist before making a state mutation

Bug: 186272717
Test: Unit Test
Change-Id: Ica3814be111708a9adf614eb4f17fe446918c0a4

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

@@ -2633,6 +2633,9 @@ public class UserManagerService extends IUserManager.Stub {
     /** @return a specific user restriction that's in effect currently. */
     @Override
     public boolean hasUserRestriction(String restrictionKey, @UserIdInt int userId) {
+        if (!userExists(userId)) {
+            return false;
+        }
         checkManageOrInteractPermissionIfCallerInOtherProfileGroup(userId, "hasUserRestriction");
         return mLocalService.hasUserRestriction(restrictionKey, userId);
     }

services/tests/servicestests/src/com/android/server/pm/UserManagerServiceTest.java

@@ -175,6 +175,13 @@ public class UserManagerServiceTest {
         assertThat(mUserManagerService.hasUserRestriction(DISALLOW_USER_SWITCH, userId)).isFalse();
     }
 
+    @Test
+    public void testHasUserRestriction_NonExistentUserReturnsFalse() {
+        int nonExistentUserId = UserHandle.USER_NULL;
+        assertThat(mUserManagerService.hasUserRestriction(DISALLOW_USER_SWITCH, nonExistentUserId))
+                .isFalse();
+    }
+
     @Test
     public void testSetUserRestrictionWithIncorrectID() throws Exception {
         int incorrectId = 1;