custom_relational_functions example does not work with browser bundle

Here is a JSFiddle with MathJS 14 using a direct copy of the [custom_relation_functions code](https://github.com/josdejong/mathjs/blob/develop/examples/advanced/custom_relational_functions.js):

https://jsfiddle.net/uonxj72q/

The output shows that the custom relation functions do not seem to be used. (E.g. when I put a debugger into them).

Oddly enough this seems to be related somehow to how the browser bundler is working, because the same code is working for me when using Vite to bundle it from node_modules.

Been trying to figure out what's going on for a couple of hours now, and frankly hitting a wall 😟.