Return false for isSplitSelectionActive() if controller not initialized

Test: unable to repro
Fixes: 342716244
Flag: EXEMPT bugfix
Change-Id: I9d7d54d5f7571286778c0e82ef4082f9b5843c1d

quickstep/src/com/android/launcher3/uioverrides/QuickstepLauncher.java

@@ -756,6 +756,9 @@ public class QuickstepLauncher extends Launcher implements RecentsViewContainer
 
     @Override
     public boolean isSplitSelectionActive() {
+        if (mSplitSelectStateController == null) {
+            return false;
+        }
         return mSplitSelectStateController.isSplitSelectActive();
     }