worker: actually track error metrics on worker handle error
Created by: Strum355
Actually track workers' handle error in the error total metric src_<banana>_processor_error_total
. Previously it wasnt doing that, because we were returning nil
from handle if no error or only a handle error occurred. How did we not ever catch this lolmao
Test plan
I tested this manually with these conditions:
- handle errors dont bubble up beyond the call to
.handle()
- infra errors do bubble up
- handle errors are counted in src__processor_error_total
- infra errors are also counted in the above