I've now also figured out why loading of chunks failed when running
using converse.js (but not when using converse.min.js or when running `make watch`).
When running `make dist`, first `converse.js` and `converse.min.js` were
built with `mode` set to `development` (via `webpack.dev.js`) and then
`converse.min.js` was again built with mode set to `production` (via
`webpack.prod.js`).
When running only one build or the other (either `webpack.dev.js` or
`webpack.prod.js`) then the loading of chunks didn't fail, so it had
something to do with running both builds back to back.
I've now removed the `.dev.js` webpack config files and instead build
the minimized and non-minimized from the same config file
`webpack.build.js`.
I did the same for the headless builds.
(Although they do load when using converse.min.js)
I wasn't able to figure out why exactly, but setting `mode` to
`production` for the `converse.js` build solved the issue.
JC Brand