Notice when using Zend\Form\Element\Number

[Fgruntjes]

The element Zend\Form\Element\Number initialises the regex validator without surrounding slash. This produces the following notice:

Notice: Undefined offset: 1 in /Volumes/WWW/service.dev/vendor/stroker/form/src/StrokerForm/Renderer/JqueryValidate/Rule/Regex.php on line 32

See Zend\Form\Element\Number:

<?php
/**
 * Zend Framework (http://framework.zend.com/)
 *
 * @link      http://github.com/zendframework/zf2 for the canonical source repository
 * @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   http://framework.zend.com/license/new-bsd New BSD License
 */

namespace Zend\Form\Element;

use Zend\Form\Element;
use Zend\InputFilter\InputProviderInterface;
use Zend\Validator\GreaterThan as GreaterThanValidator;
use Zend\Validator\LessThan as LessThanValidator;
use Zend\Validator\Regex as RegexValidator;
use Zend\Validator\Step as StepValidator;

class Number extends Element implements InputProviderInterface
{
    /**
     * Seed attributes
     *
     * @var array
     */
    protected $attributes = [
        'type' => 'number',
    ];

    /**
     * @var array
     */
    protected $validators;

    /**
     * Get validator
     *
     * @return \Zend\Validator\ValidatorInterface[]
     */
    protected function getValidators()
    {
        if ($this->validators) {
            return $this->validators;
        }

        $validators = [];
        // HTML5 always transmits values in the format "1000.01", without a
        // thousand separator. The prior use of the i18n Float validator
        // allowed the thousand separator, which resulted in wrong numbers
        // when casting to float.
        $validators[] = new RegexValidator('(^-?\d*(\.\d+)?$)');

        $inclusive = true;
        if (isset($this->attributes['inclusive'])) {
            $inclusive = $this->attributes['inclusive'];
        }

        if (isset($this->attributes['min'])) {
            $validators[] = new GreaterThanValidator([
                'min' => $this->attributes['min'],
                'inclusive' => $inclusive
            ]);
        }
        if (isset($this->attributes['max'])) {
            $validators[] = new LessThanValidator([
                'max' => $this->attributes['max'],
                'inclusive' => $inclusive
            ]);
        }

        if (!isset($this->attributes['step'])
            || 'any' !== $this->attributes['step']
        ) {
            $validators[] = new StepValidator([
                'baseValue' => (isset($this->attributes['min']))  ? $this->attributes['min'] : 0,
                'step'      => (isset($this->attributes['step'])) ? $this->attributes['step'] : 1,
            ]);
        }

        $this->validators = $validators;
        return $this->validators;
    }

    /**
     * Provide default input rules for this element
     *
     * Attaches a number validator, as well as a greater than and less than validators
     *
     * @return array
     */
    public function getInputSpecification()
    {
        return [
            'name' => $this->getName(),
            'required' => true,
            'filters' => [
                ['name' => 'Zend\Filter\StringTrim']
            ],
            'validators' => $this->getValidators(),
        ];
    }
}