Uncaught Referenceerror: Jquery Is Not Defined - Removes All Markup After Page Load?

Hi,

I'm really confused by this, has anyone experienced this before?

Every few reloads of a page triggers an error. which appears in a red box:

https://www.dropbox.com/s/t6xdlwrw6xo3975/Screenshot%202016-01-26%2009.23.29.png?dl=0

The funny thing is, it appears to start loading in the content (I can see if coming in the network tab in chrome dev tools), you can see the page being loaded in the browser, then it seems to get to the bottom and suddenly it removes all my page's markup! Seriously! This is all I am left with:

Uncaught ReferenceError: jQuery is not defined

Any ideas how I can stop it from removing my markup in this way, even if the error persists?

Looks like the DEVELOPMENT php constant is defined in your config.php or config.local.php file. Check and comment out the following code:

define('DEVELOPMENT', true);

Hah, really? But Developer mode is needed for error reporting, right?

Ok, I'll continue without and will have to try and remember to turn it on when I scratch my head later down the line :P

Hah, really? But Developer mode is needed for error reporting, right?

Ok, I'll continue without and will have to try and remember to turn it on when I scratch my head later down the line :P

Yes, but this solution will not fix your error but help you to find a reason of it