Merge "Fix NPE when converting final screen to empty screen." into sc-qpr1-dev am: 70dd01be85 am: 5980159f00

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/15583988

Change-Id: If0b63751d63e33b402152c6953bb4125f0c62597