import { AbstractControl, ValidationErrors, ValidatorFn } from '@angular/forms'; import { AbstractControlWithNotFoundType } from '../types/input-dropdown-forms.type'; export function emptyValueValidator(errorMessage: string): ValidatorFn { return (control: AbstractControl): ValidationErrors | null => { if ((control as AbstractControlWithNotFoundType).notFoundInvalid) { return { customError: errorMessage }; } return null; }; }