Added null check for Intents without action string am: 8d25bcd35c

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/services/AlternativeNetworkAccess/+/18159367

Change-Id: I1ff316b324d9155acbc10049318e201f81d17c0d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>