I have a Zod schema defined as follows:

const QuestionSchema = z.object({
  Question: z.string(),
  QuestionLevel: z.nativeEnum(QuestionLevel),
  Metadata: z.object({
    Curriculum: z.object({ Name: z.string(), Id: z.number() }),
    Qualification: z.array(z.object({ Name: z.string(), Id: z.number() })),
    Subjects: z.array(z.object({ Name: z.string(), Id: z.number() })).nonempty(),
    Modules: z.array(z.object({ Name: z.string(), Id: z.number() })).nonempty(),
    PastPaperReference: z
      .object({
        Papers: z.array(z.string()).optional(),
        Months: z.array(z.string()).optional(),
        Years: z.array(z.string()).optional(),
      })
      .optional()
      .nullable(),
  }),
});

I need to add a conditional validation to Metadata.Modules such that if QuestionLevel === "SUBJECT", then it’s okay for the Modules array to be empty or null. However, if QuestionLevel is any other value, the Modules array should be non-empty and validated according to the original schema.
How can I achieve this conditional validation for the Modules array?