Fix potential NPE in EmergencyCallbackModeExitDialog.

Ensure NPE will not crash com.android.phone process.

Test: Manual using test app provided in bug
Bug: 79995313
Change-Id: I83a5e94acdae4287e6a62558cffb586d35930b47
Merged-In: I8b899023b0977e4a8963cc536602ced4f7e43769
(cherry picked from commit 00f0c43dc4dd37d13ef614e84492783a9a6e981b)
1 file changed