Fix/flywire latest badids

[jefferis]

• fix handling of invalid ids in flywire_latestid
• reported by @paulneuro189

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a5e1269) 53.96% compared to head (a8ff26f) 54.03%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #191 +/- ## ========================================== + Coverage 53.96% 54.03% +0.07% ========================================== Files 38 38 Lines 4731 4734 +3 ========================================== + Hits 2553 2558 +5 + Misses 2178 2176 -2 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.