Andrew

As a note, it appears `superRefine` also has this issue: https://github.com/colinhacks/zod/blob/v4.1.12/packages/zod/src/v4/core/api.ts#L1489-L1509 The 'check' function is passed in, but not assigned to anything anywhere in the `bag` or `def`, making reflecting...

I'm able to reproduce this. The simplest case seems to just be, ```ts type Union = string & string[]; ``` It crashes with the following error in the console: ```...