zodToJsonSchema tries to evaluate .preprocess with `undefined` passed in

[dearlordylord]

To reproduce, use https://github.com/Firfi/zod-to-json-schema-preprocess-bug

For such code as

const idParser = z.preprocess(
  (uuid) => {
    if (typeof uuid !== 'string') throw new Error(`Expected string, got ${typeof uuid}: ${uuid}`);
    const [type, id] = uuid.split('SEPARATOR');
    return { type, id };
  }, z.object({ type: z.string(), id: z.string() }));

zodToJsonSchema(idParser) will be evaluated all right, however

if I do

const idParser2 = z.object({
  id: idParser
})

zodToJsonSchema(idParser2) starts passing undefined into preprocess (as my uuid var)

I wonder if that's expected behaviour and why it happens only when a parser is used inside z.object

[StefanTerdell]

Hello @Firfi, thanks for logging an issue. This looks like an internal Zod bug. I've logged an issue here: colinhacks/zod#1460

[StefanTerdell]

I've added a note about this issue in the readme. Closing this for lack of activity in the meantime but let's keep an eye on the issue in Zod