I usually troubleshoot these things by opening the plugin JS file in the WP editor (it's less risky editing the JS file than a PHP file) then I first ctrl+x the whole JS file to see if the issue goes away. Then I paste it back in and usually start by taking the scripts from the top of the file out - the minified ones for owl carousel, a linkify function, jQuery mobile, and a couple of IE shims. Actually I usually leave the owl carousel one in to start with otherwise it'll probably throw an error as it's called further down in the plugin script. Taking out all the scripts but owl carousel fixed the issue, so I added each back in and found that the jQuery mobile one was causing the problem. I left it removed for now and it's working fine on his site.
It doesn't look like their site has jQuery mobile, but it seems as though something in one of their plugins doesn't like the jQ mobile script and threw an error. There's not much we can do apart from letting him know what we did and giving him directions on how to remake that change if he updates the plugin in future. I don't think it's worth adding a setting to disable it just based on a rare case like this, has anyone else had an issue related to that script that you can remember? This is the script that I removed near the top of the JS file:
It doesn't look like their site has jQuery mobile, but it seems as though something in one of their plugins doesn't like the jQ mobile script and threw an error. There's not much we can do apart from letting him know what we did and giving him directions on how to remake that change if he updates the plugin in future. I don't think it's worth adding a setting to disable it just based on a rare case like this, has anyone else had an issue related to that script that you can remember? This is the script that I removed near the top of the JS file: