Trying to use javascript mode and we are receiving an error in the server l

Trying to use javascript mode and we are receiving an error in the server logs.

[qtp1208189031-20]
INFO com.vaadin.flow.router.RouteNotFoundError - Couldn’t find route for ‘ace-builds/src-min-noconflict/mode-javascript.js’

Any idea what may be wrong?

Our VaadinApplicationServlet is not deployed at the root, it is deployed at /app. If I change the above route to be an absolute path instead of relative to /app, then the resource is found.