Fatal error on new version

Hi,

I started experiencing a critical error on my website after WPP was auto-updated to 5.3.4 last night. The site normally shows a list of the most popular custom posts, however, I’ve had to deactivate the plugin due to this error. Any suggestions on what the issue is and how I can resolve it so I can switch it back on again? I’ve been using the plugin for a long time (many years) with no issues so it’s definitely somethign to do with the upgrade. WordPress auto message on the error below also with some additional details.

Thanks for any help you can provide.

Howdy!

Since WordPress 5.2 there is a built-in feature that detects when a plugin or theme causes a fatal error on your site, and notifies you with this automated email.

In this case, WordPress caught an error with one of your plugins, WordPress Popular Posts.

First, visit your website (https://www.shortkidstories.com/) and check for any visible issues. Next, visit the page where the error was caught (https://www.shortkidstories.com/wp-login.php) and check for any visible issues.

Please contact your host for assistance with investigating this issue further.

If your site appears broken and you can’t access your dashboard normally, WordPress now has a special “recovery mode”. This lets you safely login to your dashboard and investigate further.

https://www.shortkidstories.com/wp-login.php?action=enter_recovery_mode&rm_token=

To keep your site safe, this link will expire in 1 day. Don’t worry about that, though: a new link will be emailed to you if the error occurs again after it expires.

When seeking help with this issue, you may be asked for some of the following information:
WordPress version 5.7.2
Current theme: ShortKidStories (version 1.1) Current plugin: WordPress Popular Posts (version 5.3.4) PHP version 7.0.33

The page I need help with: [log in to see the link]