let's me show you this method :

   /**
     * Get showCustomFormErrors
     * 
     * @return bool
     */
    public function getShowCustomFormErrors()
    {
        if (null === $this->_showCustomFormErrors) {
            if (null === ($how =  $this->getOption('showCustomFormErrors'))) {
                $this->setShowCustomFormErrors($this->_defaults['showCustomFormErrors']);
            } else {
                $this->setShowCustomFormErrors($show);
                $this->removeOption('showCustomFormErrors');
            }
        }
    }

1/ this method is apparently a getter and there is no return instruction. 2/ We have two variables : $how and $show.

Same errors with getOnlyCustomFormErrors().