resolver-is-async

[wizzard] resolver "<name>" returned a promise. This expression is evaluated synchronously - a
when, a transition guard or a repeat source - and cannot wait for it. Make <name> synchronous, or
move the asynchronous work into the step's validate or load. …/errors/resolver-is-async

Thrown as a WizardError with op: 'evaluate'. Any value with a then method counts as a promise here, so a promise from another library is refused the same way as a native one.

Some expressions are read while the engine works out which steps exist and where a move leads: a step’s when, the guards in on.next, a repeat group’s repeat.over and its ctx. Those answers feed the progress bar and the list of steps a binding renders, so they are computed synchronously, and a resolver used there has to return its value rather than a promise of one.

validate and load are the places built for waiting. They run inside a navigation, the wizard reports itself busy while they do, and a newer move supersedes them. A check that has to go to the network belongs there. A condition that depends on something fetched reads a value that is already present instead: fetch it before createWizard and pass it in data or ctx, or write it with set once it arrives, and let the when compare it with $get.

isSync(expr) from @wizzard-packages/core tells whether an expression contains any $ref at all, which is the question to ask of a flow that arrives from a server before rendering it.