Establish bundle behaviour to avoid minification/uglification and ensure sourcemaps

[cefn]

This issue is to ensure that the bundled versions for ESM and CommonJs still contain their fully-qualified names and are not uglified/minified.

Compressing the javascript source is not necessary for Node, and in the case of any real-world browser deployment it would be bundled and minified into the source by the consuming project.

This also means in general that even without sourcemaps it would be easier to make sense of stack traces and debugging.