Guard against the NPE in getTransitionType()

Bug: 232852095
Test: Go to fingerprint enrolling page and see the transition stays the
same(sliding) after this change.

Change-Id: I259eb4362b273f6b297e94d59d6720a9d6bf6373

src/com/android/settings/core/SettingsBaseActivity.java

@@ -260,6 +260,9 @@ public class SettingsBaseActivity extends FragmentActivity implements CategoryHa
     }
 
     private int getTransitionType(Intent intent) {
+        if (intent == null) {
+            return TransitionType.TRANSITION_NONE;
+        }
         return intent.getIntExtra(EXTRA_PAGE_TRANSITION_TYPE, TransitionType.TRANSITION_NONE);
     }
 }