Fix Settings crash when setting a null ringtone am: ec3ae8bb am: 39759724

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/18400413



Change-Id: I62d726f6228d77cc8f0fac314743e41f7897b714
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>