Skip launching task if there is no task

Bug: 75974298
Change-Id: I60a6c27c4dfb983d0f6e9832fb3be1e714cea2e7
diff --git a/quickstep/src/com/android/quickstep/QuickScrubController.java b/quickstep/src/com/android/quickstep/QuickScrubController.java
index a154b29..d263fbf 100644
--- a/quickstep/src/com/android/quickstep/QuickScrubController.java
+++ b/quickstep/src/com/android/quickstep/QuickScrubController.java
@@ -84,7 +84,10 @@
         }
         int page = mRecentsView.getNextPage();
         Runnable launchTaskRunnable = () -> {
-            ((TaskView) mRecentsView.getPageAt(page)).launchTask(true);
+            TaskView taskView = ((TaskView) mRecentsView.getPageAt(page));
+            if (taskView != null) {
+                taskView.launchTask(true);
+            }
         };
         int snapDuration = Math.abs(page - mRecentsView.getPageNearestToCenterOfScreen())
                 * QUICKSCRUB_END_SNAP_DURATION_PER_PAGE;