Add non null check on mViewPager

Bug: 232034849
Test: N/A
Change-Id: I304088baf84dd6f65e096f610ebe11df036ae8d3

src/com/android/launcher3/allapps/BaseAllAppsContainerView.java

@@ -326,7 +326,7 @@ public abstract class BaseAllAppsContainerView<T extends Context & ActivityConte
     }
 
     protected boolean isPersonalTab() {
-        return mViewPager.getNextPage() == 0;
+        return mViewPager == null || mViewPager.getNextPage() == 0;
     }
 
     /**