+ case 400:
+ // Probably invalid data (bad Unicode chars or coords) that
+ // cannot be resolved by just sending again.
+ //
+ // It could also be rate limiting, but retrying immediately
+ // won't help much with that, so we'll discard for now.
+ // If a facility for retrying things later comes up in future,
+ // we can detect the rate-limiting headers and use that.
+ //
+ // Discard the message permanently.
+ return true;
+ break;