Function singletonMap

apps/api/src/lib/errors/api-errors.factory.ts:17–20

(
  field: string,
  message: string
)

 * for multi-field cases.
 */
const singletonMap = (
  field: string,
  message: string
): Record<string, string> => ({ [field]: message });

export const ApiErrors = {
  validation: (