Hustle javascript error

I have written an integration for this plugin with The Newsletter plugin. All is working well on my local server. But when i uploaded to my remote server a javascript error is occuring that prevents me interacting with hustle as admin. The error on page load of a hustle admin page is that a token is unexpected and then on clicking a button, e.g. create new popup or add integration button, the error is a reference error that SUI is not a valid property. I do not currently have the exact error output to hand but can post it if needed. I have a hunch this is to do with SELECT2. I have tried uninstalling plugins and deleting and reinstalling hustle. Help appreciated.

Ceri