isZodError: check if error.errors is actually an array

ZodError type expects errors prop to be an array

export declare class ZodError<T = any> extends Error {
    issues: ZodIssue[];
    get errors(): ZodIssue[];
    constructor(issues: ZodIssue[]);
    format(): ZodFormattedError<T>;
    format<U>(mapper: (issue: ZodIssue) => U): ZodFormattedError<T, U>;
    static create: (issues: ZodIssue[]) => ZodError<any>;
    toString(): string;
    get message(): string;
    get isEmpty(): boolean;
    addIssue: (sub: ZodIssue) => void;
    addIssues: (subs?: ZodIssue[]) => void;
    flatten(): typeToFlattenedError<T>;
    flatten<U>(mapper?: (issue: ZodIssue) => U): typeToFlattenedError<T, U>;
    get formErrors(): typeToFlattenedError<T, string>;
}

And parseErrorSchema function expects an array:

https://github.com/react-hook-form/resolvers/blob/f7a4fd46af51a2a732c10ed652f5abfa532f4198/zod/src/zod.ts#L8-L11

Recently, we encountered an issue where the props can be undefined for some reason. I propose this PR to add a stricter check to prevent unexpected circumstances where the error.errors object is not an array.

Resolve #696

react-hook-form / resolvers

isZodError: check if error.errors is actually an array #697