PHP warnings are not breaking errors. If you use PHP 8.1+ you'd better hide the warnings by adding the command below to wp-content.php file of your WordPress installation.
Upon updating PHP to version 8, Toolset Types and Layouts cause a site crash, generating fatal errors like: "Uncaught TypeError: Cannot access offset of type string on string."
Solution:
Identified database corruptions causing errors in loading Layouts. To resolve, delete specific options from the options table:
Validation of the featured image in the Toolset Forms was triggering an error.
Solution:
The issue was that the PHP function 'getimagesize' expects the param to be an actual object and in the error log you shared this parameter is empty.
I deducted that this happened when you try to submit the form without the featured image, then getimagesize will try to check the size of null and error out.
I added a check to see if the field _featured_image is set before checking for the size and that fixed the issue.
