can convert preprocess to ts

[Hoang The Hung]

z.preprocess(
                (a) => parseInt(z.string().parse(a), 10),
                z.number().positive().max(100)
              ),

error:

console.log
    ZodError: [
      {
        "code": "invalid_type",
        "expected": "string",
        "received": "undefined",
        "path": [],
        "message": "Required"
      }
    ]
        at handleResult (/Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod/lib/types.js:29:23)
        at ZodString.safeParse (/Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod/lib/types.js:140:16)
        at ZodString.parse (/Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod/lib/types.js:120:29)
        at Object.transform (/Users/owner/Documents/source-code/private/express-zod-api/tests/unit/client.spec.ts:19:44)
        at ZodEffects._parse (/Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod/lib/types.js:2261:38)
        at ZodEffects._parseSync (/Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod/lib/types.js:109:29)
        at ZodEffects.safeParse (/Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod/lib/types.js:139:29)
        at ZodEffects.isOptional (/Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod/lib/types.js:276:21)
        at /Users/owner/Documents/source-code/private/express-zod-api/node_modules/zod-to-ts/dist/index.cjs:141:81
        at Array.map (<anonymous>)

[Sachin Raja]

Looks like this is a Zod issue? We shouldn't be getting an error for calling isOptional on a schema.