Accouting process can fail if a subscriber is manually added to the DB

[matt9j]

Error log:

Jun 11 13:58:11 cobble haulage[29636]: thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: UserLookupError', haulage/src/accounter.rs:100:65
Jun 11 13:58:11 cobble haulage[29636]: note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Jun 11 13:58:11 cobble haulage[29636]:   aggregator: user
Jun 11 13:58:11 cobble haulage[29636]:    aggregation: 10.45.1.8
Jun 11 13:58:11 cobble haulage[29636]:     Jun 11 20:58:11.998 ERRO Failed to initialize reporter, error: Failed to lookup user, id: 10.45.1.8
Jun 11 13:58:12 cobble haulage[29636]:   accounter: user
Jun 11 13:58:12 cobble haulage[29636]:    Jun 11 20:58:12.004 ERRO Failed to dispatch, error: channel closed