Simplify logic for Tandem.required vs Tandem.errorOnFailedValidation, see https://github.com/phetsims/phet-io/issues/1477
Simplify logic for Tandem.required vs Tandem.errorOnFailedValidation, see https://github.com/phetsims/phet-io/issues/1477

phetsims/sun,phetsims/sun,phetsims/sun