Regarding sudden error at random times can happen for several reasons,

1. Uses of Caching plugin (WP Rocket, WP smush, yoast etc)
2. Uses of minify plugin
3. Low budget servers (temp server, free server, low-cost server)
4. Server issue (server is unable to handle the request on your site at times)
5. Third-party plugin conflict
6. Theme conflict
7. Plugin requirement not fulfilled
8. you have removed some data from your reactive builder or from your posts for e.g. (you have removed a taxonomy or meta from the post type) or deleted a grid template but those data are selected on your search page. To ensure if this is the issue just create a new shortcode.
9. You have copied your site DB data from another site or from your local development which might be caused some missing/corrupted data in your DB. As a result reactive pro plugin can cause console errors. In most of the time the plugin responsible for the data should cause issues so you should either double-check them or create those data again if possible.

To find what caused your issue you need to check one by one. for server related issue please contact with your server administrator.

Due to our limited support scope (Item Support Policy) we can't help you to fix this issues.