fix(typescript): compatible with 4.3

Created by: smasala

Fixes (see: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-3.html):

TS4114: This member must have an 'override' modifier because it overrides a member in the base class 'Error'.
    65 |  */
    66 | export class RequiredError extends Error {
  > 67 |     name: "RequiredError" = "RequiredError";
       |     ^^^^
    68 |     constructor(public field: string, msg?: string) {
    69 |         super(msg);
    70 |     }

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