Element with bgcolor attribute creates critical error

[bagofarms]

When phpally grabs the style of an element, the following condition is evaluated: https://github.com/cidilabs/phpally/blob/master/src/Rule/BaseRule.php#L170

if($element->hasAttribute('bgcolor') &&  in_array($element->tagName, $this->deprecated_style_elements)) {
	$style['background-color'] = $element->getAttribute('bgcolor');
}

If the element does not have a bgcolor attribute, php does not evaluate the second part of the condition, and the code continues executing without issue. If the element does have a bgcolor attribute, the in_array portion of the condition is evaluated, causing a critical error:

Uncaught PHP Exception TypeError: "in_array(): Argument #2 ($haystack) must be of type array, null given" at /var/www/html/vendor/cidilabs/phpally/src/Rule/BaseRule.php line 169

Which appears to be saying that $this->deprecated_style_elements is null. I did a search for deprecated_style_elements in the rest of the codebase, and did not find another mention of it, so it appears that this value is never defined, hence why it is null. It seems like the in_array check isn't really necessary, since it shouldn't matter what element we're pulling the bgcolor attribute from.

[bagofarms]

In the course that was exhibiting this issue, I removed all instances of the bgcolor attribute and the UDOIT scan was able to complete successfully.