Error on our Shopify store stopping account login from loading

We've run into a problem on our Shopify store where our customer login/portal isn't working or loading, and is causing support issues. We believe this could be due to an error in the theme.

The website is https://lifearmour.co.uk/

Whenever a user clicks 'login' or 'register' the page fails to load.

We're looking for someone to help fix the issue, and we are hoping this is a quick fix, but the budget can be increased depending on the work required and the agreement upfront.