an easier way to make error maps for Zod

makeErrorMap.ts

import { z } from 'zod'

type ErrorCode = z.ZodIssueCode | 'required'
type Message = string
type MessageBuilder = ( data: unknown, options?: any[] ) => Message
type ErrorRecord = Partial<Record<ErrorCode, Message | MessageBuilder>>
function makeErrorMap ( errorRecord: ErrorRecord ): z.ZodErrorMap {
    return ( issue, ctx ) => {
        const options = issue.code === 'invalid_enum_value'
            ? issue.options : undefined

        const errorCode: ErrorCode =
            issue.code === 'invalid_type' && ctx.data === undefined
                ? 'required' : issue.code

        const messageOrBuilder = errorRecord[ errorCode ]
        const message = typeof messageOrBuilder === 'function'
            ? messageOrBuilder( ctx.data, options ) : messageOrBuilder

        return message ? { message } : { message: ctx.defaultError }
    }
}

const errorMap = makeErrorMap( {
    required: 'Custom required message',
    invalid_type: data => `${ JSON.stringify( data ) } is not a valid type`,
    invalid_enum_value: ( data, options ) =>
        `${ JSON.stringify( data ) } is not a valid enum value. Valid options: ${ options?.join( ' | ' ) }`,
    invalid_date: data => {
        const value = data instanceof Date ? data.valueOf() : JSON.stringify( data )
        return `${ value } is not a valid date`
    },
} )

function dataOrError ( result: z.SafeParseReturnType<unknown, unknown> ) {
    return result.success ? result.data : result.error.issues[ 0 ].message
}

{
    console.group( 'z.string' )
    const schema = z.string( { errorMap } )
    console.log( dataOrError( schema.safeParse( 'foo' ) ) )
    console.log( dataOrError( schema.safeParse( undefined ) ) )
    console.log( dataOrError( schema.safeParse( 42 ) ) )
    console.log( dataOrError( schema.safeParse( [ 42 ] ) ) )
    console.groupEnd()
    console.log()
}
{
    console.group( 'z.number' )
    const schema = z.number( { errorMap } )
    console.log( dataOrError( schema.safeParse( 42 ) ) )
    console.log( dataOrError( schema.safeParse( undefined ) ) )
    console.log( dataOrError( schema.safeParse( 'foo' ) ) )
    console.log( dataOrError( schema.safeParse( { foo: 'foo' } ) ) )
    console.groupEnd()
    console.log()
}
{
    console.group( 'z.enum' )
    const schema = z.enum( [ 'public', 'unlisted', 'private' ], { errorMap } )
    console.log( dataOrError( schema.safeParse( 'unlisted' ) ) )
    console.log( dataOrError( schema.safeParse( undefined ) ) )
    console.log( dataOrError( schema.safeParse( null ) ) )
    console.log( dataOrError( schema.safeParse( 'foo' ) ) )
    console.groupEnd()
    console.log()
}
{
    console.group( 'z.date' )
    const schema = z.date( { errorMap } )
    console.log( dataOrError( schema.safeParse( new Date ) ) )
    console.log( dataOrError( schema.safeParse( undefined ) ) )
    console.log( dataOrError( schema.safeParse( '2023-01-13' ) ) )
    console.log( dataOrError( schema.safeParse( null ) ) )
    console.log( dataOrError( schema.safeParse( new Date( '' ) ) ) )
    console.groupEnd()
    console.log()
}
/* 
logs:
z.string
    foo
    Custom required message
    42 is not a valid type
    [42] is not a valid type

z.number
    42
    Custom required message
    "foo" is not a valid type
    {"foo":"foo"} is not a valid type

z.enum
    unlisted
    Custom required message
    null is not a valid type
    "foo" is not a valid enum value. Valid options: public | unlisted | private

z.date
    2023-01-13T15:41:37.771Z
    Custom required message
    "2023-01-13" is not a valid type
    null is not a valid type
    NaN is not a valid date
*/