Patch npe in TaskbarAllAppsController

b/234617317#comment3

Bug: 234617317
Test: manual
Change-Id: I7cff0df86db4fdf58b33240594784598950f1a88
diff --git a/quickstep/src/com/android/launcher3/taskbar/allapps/TaskbarAllAppsController.java b/quickstep/src/com/android/launcher3/taskbar/allapps/TaskbarAllAppsController.java
index 6fd98db..c56ac5b 100644
--- a/quickstep/src/com/android/launcher3/taskbar/allapps/TaskbarAllAppsController.java
+++ b/quickstep/src/com/android/launcher3/taskbar/allapps/TaskbarAllAppsController.java
@@ -171,8 +171,8 @@
      * This method should be called after an exit animation finishes, if applicable.
      */
     void maybeCloseWindow() {
-        if (AbstractFloatingView.getOpenView(mAllAppsContext, TYPE_ALL) != null
-                || mAllAppsContext.getDragController().isSystemDragInProgress()) {
+        if (mAllAppsContext != null && (AbstractFloatingView.hasOpenView(mAllAppsContext, TYPE_ALL)
+                || mAllAppsContext.getDragController().isSystemDragInProgress())) {
             return;
         }
         mProxyView.close(false);