[automerger skipped] Fix NullPointerException on addErrorCode when input is...

[automerger skipped] Fix NullPointerException on addErrorCode when input is Invalid error code am: ad90e1bf am: c2cdb2c7 -s ours am: 9e938beb -s ours

am skip reason: Change-Id I43b8415ab98b4cf6520c3240dc544a9f62730a4e with SHA-1 ec4786a7 is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/11987398

Change-Id: I631c0db3d1c506be7e3921207a582de8899ff3af