Good news - there are two alternative simple solutions!
Short version:
- Try a different browser such as Chrome. It works for sites such as Meetup.com that my Safari won't load.
- Turn off JavaScript and reload the page. It should now load, though with some elements missing. See below.
Explanation
The message "Application error: a client-side exception has occurred (see the browser console for more information)" indicates a JavaScript error. Basically, the website you are trying to load has been badly coded and does not conform to the standards your browser expects.
Some browsers are more tolerant of errors than others. For example, whilst safari 13 loads Meetup.com and then switches to the error message, Chrome loads it without complaint.
By turning JavaScript off in Safari (see below) you can load the page without an error occurring, although some content will be missing. In the case of Meetup.com this is generally media content such as images and videos. Note: JavaScript is not the same thing as java!
If you can understand JavaScript error messages, you might want to open the Safari JavaScript Console and send that to the website owner - but if you're not a JavaScript developer, its pretty daunting and rather meaningless!
Detailed Instructions
If choosing option 2 to load the site in Safari with JavaScript turned off, you can just open Safari Preferences (from the menu bar, or type Command + comma. Go to the Security tab and un-tick "Enable JavaScript. Now reload the website. It should load, but without some rich content.
Once you've reloaded the page, you can re-enable JavaScript to continue getting rich content on other websites.
Bonus Info
If you want to make life easier for yourself, JavaScript can be enabled and disabled from Safari's optional Developer menu.
Most settings here should be ;eft alone f you don't know what you're doing, but is has some useful shortcuts for disabling JavaScript, emptying the caches, and viewing the JavaScript console (where all the errors can be seen.
To enable the Developer menu, open Safari Preferences, click on the Advanced tab, and enable "Show Develop menu in menu bar" by ticking the box. You now have quick access to the settings we have discussed above.
Hope this sorts your issue.