PHP Fatal error: Uncaught ArgumentCountError

When I post a long comment, for example the size of the 5 short paragraphs on https://lorem2.com/, it just hangs and doesn’t post. When I refresh the page, I see this is the error displayed there (I’ve enabled WP_DEBUG for dev). I have a char limit of 1000 on comments and I had 158 less when posting those paragraphs.

[07-Dec-2018 11:00:35 UTC] PHP Fatal error:  Uncaught ArgumentCountError: Too few arguments to function WpdiscuzHelper::getCommentExcerpt(), 2 passed in /Users/myuser/Sites/wptest/wp-content/themes/customtheme/wpdiscuz/class.WpdiscuzWalker.php on line 55 and exactly 3 expected in /Users/myuser/Sites/wptest/wp-content/plugins/wpdiscuz/utils/class.WpdiscuzHelper.php:192
Stack trace:
#0 /Users/myuser/Sites/wptest/wp-content/themes/customtheme/wpdiscuz/class.WpdiscuzWalker.php(55): WpdiscuzHelper::getCommentExcerpt('<p>Lorem ipsum ...', '90_0')
#1 /Users/myuser/Sites/wptest/wp-includes/class-wp-walker.php(145): WpdiscuzWalker->start_el('<div id="wc-com...', Object(WP_Comment), 1, Array)
#2 /Users/myuser/Sites/wptest/wp-includes/class-walker-comment.php(135): Walker->display_element(Object(WP_Comment), Array, '5', 0, Array, '<div id="wc-com...')
#3 /Users/myuser/Sites/wptest/wp-includes/class-wp-walker.php(370): Walker_Comment->display_element(Object(WP_Comment), Array, '5', 0, Array, '<div id="wc-com...')
#4 /Users/myus in /Users/myuser/Sites/wptest/wp-content/plugins/wpdiscuz/utils/class.WpdiscuzHelper.php on line 192

Is this is a bug or something that requires some configuration? The comment is visible in the back end but on the page there’s only this error along with other styles of the page looking haywire.