Little fix in form() function

Hello @DamienMcKenna,

There is one small syntax problem in function form(array $element = array()) (Line 163 of src\Plugin\metatag\Tag\MetaNameBase.php)

I think this "if" condition is not perfect:

// Optional handling for images.
if (!empty($this->type() === 'image')) {

This should be:

// Optional handling for images.
if ((!empty($this->type())) && ($this->type() === 'image')) {

I have created a patch file, please review it and provide your thoughts on this.

Thank you,