method ZodError.prototype.flattenimport { ZodError } from "https://dotland.deno.dev/x/zod@v3.17.3/mod.ts"; flatten(): typeToFlattenedError<T>flatten<U>(mapper?: (issue: ZodIssue) => U): typeToFlattenedError<T, U>flatten<U = string>(mapper?: (issue: ZodIssue) => U): anyReturnstypeToFlattenedError<T>Type ParametersUParametersoptionalmapper: (issue: ZodIssue) => UReturnstypeToFlattenedError<T, U>Type ParametersoptionalU = stringParametersoptionalmapper: (issue: ZodIssue) => U = [UNSUPPORTED]Returnsany