bun loads code all code in strict mode by default, which is intentional (es modules define this as spec, and node esm does this too). strict mode doesn't allow a number of things like undeclared variables.

I wonder if there's a nice way we can enable sloppy mode.

Probably the better fix here is to detect usages of sloppy mode features and build as CommonJS in that case

It seems that the usual way of declaring that you want to use strict mode is adding "use strict"; to the beginning of a script or a function.

https://www.w3schools.com/js/js_strict.asp

I've checked that node.js supports this!

I kinda like the idea that strict mode is opt out and not opt in because it helps building more modern projects.

Probably the better fix here is to detect usages of sloppy mode features and build as CommonJS in that case

This has since been implemented

To enable sloppy mode, use CommonJS in your module and don't include "use strict" at the top. Or, make the file extension .cjs

We're unlikely to change this at this stage tbh