Fixes AssistOrbController crash

AssistOrbController caused a crash by trying to remove a view that was
not attached. This change adds a check if the view is attached before
removal.

Test: Tested locally
BUG: 195902117
FIX: 195902117
Change-Id: Ibc65a9b1789c7ee629c28de31392fffc0536ed70

packages/SystemUI/src/com/android/systemui/assist/AssistOrbController.java

@@ -57,7 +57,9 @@ public class AssistOrbController {
         public void run() {
             mView.removeCallbacks(this);
             mView.show(false /* show */, true /* animate */, () -> {
-                mWindowManager.removeView(mView);
+                if (mView.isAttachedToWindow()) {
+                    mWindowManager.removeView(mView);
+                }
             });
         }
     };