Fix null dereference in SweepInterpreterCaches am: 6a05d70393

Original change: https://android-review.googlesource.com/c/platform/art/+/2194755

Change-Id: I9a881ebff6ee8b2696ca36a360a098147352c7e2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>