How to deploy a Dart web application to a non-root URI?

Question

JavaScript

The app works great locally.
When loaded in a browser, it swears at

Uncaught TypeError: Cannot read property 'gac' of null

The specific name of the property does not matter, since, as you know, the code for release is minified and obfuscated.
When uploading non-minimized code, it tries to get separate files from the server from the root, although the application itself is not located at the root.
What exactly to upload and how to place the URI on the production server?
main.dart.js
packages/*
something else?
or packages/*not needed?
somewhere you need to specify the base URI so that it does not climb to the root of the site?
In other words - where to upload the results of the team's work
webdev build
AND how to adjust the URI.