Undefined array key

When customizing seperate accordions with colors, a PHP warning appears as of PHP 8.0 and above. It will turn in to an error in a future version of php.

Warning
: Undefined array key "color" in
/wp-content/plugins/advanced-accordion-block/advanced-accordion-block.php
on line
146


Warning
: Undefined array key "color" in
/wp-content/plugins/advanced-accordion-block/advanced-accordion-block.php
on line
148

I have done a quick and dirty patch that checks if the key is set, and if not, sets the custom css to an invalid property the browser will ignore.

/*line 140 in advanced-accordion-block/advanced-accordion-block.php*/
// separate accordion
	public function aagb_render_group_accordion($attributes, $content){
		if(! is_admin(  )){
			$handle = 'aagb-'.$attributes['uniqueId'];
			$custom_css = '';
			// container
			if(isset($attributes['activeAccordionBorder']['color'])){
			    $activeAccordionBorderColor = $attributes['activeAccordionBorder']['color'];
			} else {
			    $activeAccordionBorderColor = 'no-val';
			}
			if(isset($attributes['activeAccordionBorder']['width'])){
			    $activeAccordionBorderWidth = $attributes['activeAccordionBorder']['width'];
			} else {
			    $activeAccordionBorderWidth = 'no-val';
			}
			if(isset($attributes['activeAccordionBorder']['style'])){
			    $activeAccordionBorderStyle = $attributes['activeAccordionBorder']['style'];
			} else {
			    $activeAccordionBorderStyle = 'no-val';
			}
			
			$custom_css .= '.aagb_accordion_'.$attributes['uniqueId'].' .aagb__accordion_active{ border-color: '.$activeAccordionBorderColor.' !important; border-width: '.$activeAccordionBorderWidth.'!important; border-style: '.$activeAccordionBorderStyle.'!important; }';
			// body
			$custom_css .= '.aagb_accordion_'.$attributes['uniqueId'].' .aagb__accordion_body--show{ border-top-color: '.$activeAccordionBorderColor.' !important; border-top-width: '.$activeAccordionBorderWidth.'!important; border-top-style: '.$activeAccordionBorderStyle.'!important; }';

			$this->aagb_render_inline_css( $handle, $custom_css );
		}
		return $content;
	}