Adding nullcheck while launching task during quickswitch

Bug: 159758771
Change-Id: I04dd1432a1acc49cbc776c89e95cfb1ee6e88061

quickstep/recents_ui_overrides/src/com/android/quickstep/BaseSwipeUpHandler.java

@@ -15,6 +15,8 @@
  */
 package com.android.quickstep;
 
+import static android.widget.Toast.LENGTH_SHORT;
+
 import static com.android.launcher3.config.FeatureFlags.ENABLE_QUICKSTEP_LIVE_TILE;
 import static com.android.launcher3.util.Executors.MAIN_EXECUTOR;
 import static com.android.launcher3.util.VibratorWrapper.OVERVIEW_HAPTIC;
@@ -27,11 +29,13 @@ import android.graphics.Rect;
 import android.os.Build;
 import android.util.Log;
 import android.view.MotionEvent;
+import android.widget.Toast;
 
 import androidx.annotation.CallSuper;
 import androidx.annotation.UiThread;
 
 import com.android.launcher3.DeviceProfile;
+import com.android.launcher3.R;
 import com.android.launcher3.statemanager.StatefulActivity;
 import com.android.launcher3.testing.TestProtocol;
 import com.android.launcher3.util.VibratorWrapper;
@@ -138,10 +142,10 @@ public abstract class BaseSwipeUpHandler<T extends StatefulActivity<?>, Q extend
             mRecentsView.getNextPageTaskView().launchTask(false /* animate */,
                     true /* freezeTaskList */);
         } else {
-            int taskId = mRecentsView.getNextPageTaskView().getTask().key.id;
             if (!mCanceled) {
-                TaskView nextTask = mRecentsView.getTaskView(taskId);
+                TaskView nextTask = mRecentsView.getNextPageTaskView();
                 if (nextTask != null) {
+                    int taskId = nextTask.getTask().key.id;
                     mGestureState.updateLastStartedTaskId(taskId);
                     boolean hasTaskPreviouslyAppeared = mGestureState.getPreviouslyAppearedTaskIds()
                             .contains(taskId);
@@ -158,6 +162,10 @@ public abstract class BaseSwipeUpHandler<T extends StatefulActivity<?>, Q extend
                                     mRecentsAnimationController.finish(true /* toRecents */, null);
                                 }
                             }, MAIN_EXECUTOR.getHandler());
+                } else {
+                    mActivityInterface.onLaunchTaskFailed();
+                    Toast.makeText(mContext, R.string.activity_not_available, LENGTH_SHORT).show();
+                    mRecentsAnimationController.finish(true /* toRecents */, null);
                 }
             }
             mCanceled = false;