app/services/asserts/NullableAssert.ts

import type {AssertRule} from "~/types/interfaces";
import { useI18n } from 'vue-i18n';

export class NullableAssert implements AssertRule {
  supports(key: string): boolean {
    return key === 'nullable';
  }

  createRule(criteria: boolean): (value: any) => true | string {
    const { t } = useI18n();
    return (value: any) =>
      !criteria ? !!value || t('required') : true;
  }
}