nav-superseded

{ ok: false, reason: 'superseded', code: 'nav-superseded', url: '…/errors/nav-superseded' }

Returned, not thrown, by next(), back() and go(), to the earlier of two moves. The later one runs to its own result. Nothing the earlier move computed is written.

Every move takes a turn when it starts. When a second one begins while the first is still awaiting a validator, a guard or a load, the first loses its turn, and when its await settles it stops instead of committing - a plugin hook, validator, guard or loader that throws by then is not rethrown either. A double-clicked Next is the everyday case: one move, one superseded. A move into a repeat group is also superseded when set() changes the items under it while it waits.

It is not a failure to show anyone. Ignore it, or disable the control while isBusy is true so the second call is never made. Do not retry the move: the one that superseded it is already running.