private function existingPropertyVirtualOrFail(string $propertyName): void
    {
        assert($this->propertyExists($propertyName));
        if (!$this->isExistingPropertyVirtual($propertyName)) {
            throw new NonVirtualPropertyException($propertyName);
        }
    }
private function existingPropertyVirtualOrFail(string $propertyName): void
    {
        assert($this->propertyExists($propertyName));
        if (!$this->isExistingPropertyVirtual($propertyName)) {
            throw new NonVirtualPropertyException($propertyName);
        }
    }
private function existingPropertyVirtualOrFail ( string $ propertyName ) : void { assert ( $ this -> propertyExists ( $ propertyName ) ) ; if ( ! $ this -> isExistingPropertyVirtual ( $ propertyName ) ) { throw new NonVirtualPropertyException ( $ propertyName ) ; } }
Fail if an existing property is not virtual.

@param string $propertyName

@throws NonVirtualPropertyException
Fail if an existing property is not virtual .