[DO NOT MERGE] Fix Settings crash when setting a null ringtone am: d94b73b304

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/18356598

Change-Id: Id5b31b30de1883d7d673fc0de60419fca7a22e86
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>