Undefined index: figure_closing on line 164

Dear Crazy Lazy team,

I’m having some trouble with my website lately (getting errors 500 very often). While investigating, what might cause the problems, I found the following error:

Notice: Undefined index: figure_closing in [root folder]/wp-content/plugins/crazy-lazy/inc/class-crazylazy.php on line 164

The line 164 contains the following code:

. $matches['closing'] . '>' . $matches['figure_closing'] . '<noscript>' . $matches['all'] . '</noscript>';

Do you know what causes a problem here and how to fix this?

Thanks in advance!