Deploying with mup: Running Meteor on TLD

We’ve been running our Meteor server on a subdomain so far, i.e. on The same server also listens to other subdomains like, for historical reasons. In the mup setup, is being used as the server address, and the additional domains are setup via the proxy config. This works just fine.

I now wanted to configure the server to use the TLD as well, i.e. But if I do this, I get a blank page for that domain, and an error in the console that looks like this:

Uncaught DOMException: Failed to execute 'add' on 'DOMTokenList': The token provided must not be empty.

It seems as if some code tries to get a subdomain and fails because there is none. Is there a way to change this?

(Of course, I could setup an S3 bucket and setup a static forward from to, but I am wondering if there’s another option where the Meteor server actually listens on the TLD.)