TypeError: Cannot read property 'ColumnNames' of undefined

[moltar]

I am not sure if the issue is with esbuild or the underlying library, but I am running into a peculiar error for which I have a repro here:

https://github.com/moltar/zapatos-issue-10

Transpiling with tsc works fine.

Reference issue in the library repo: jawj/zapatos#75

Thank you!

[evanw]

The problem happens when node_modules/zapatos/db.mjs (an ESM file) imports node_modules/zapatos/db.js (a CommonJS file). I think the underlying issue is #532, which is already tracked. Basically there are two conflicting approaches for handling importing a CommonJS file into an ESM file. Some JavaScript tools do this one way and other JavaScript tools do this another way. It's a big mess.

The way node works is that the default export is always equal to the value of the CommonJS file's module.exports property without any exceptions. Some other JavaScript tools (but not node) support CommonJS files that have been converted from ESM format to CommonJS format. These ones are marked by setting module.exports.__esModule to true. For these modules, all properties on module.exports behave like named exports as if the file was in ESM format. And if there is no module.exports.default property, then there is no export named default.

So this should be considered a bug in esbuild in that the behavior isn't matching node. But it's not super straightforward to fix this because a trivial fix would break esbuild's ESM-to-CommonJS transform which esbuild relies on internally. Webpack has an approach where they try to support both of these behaviors and use heuristics to determine which approach to apply when. I assume esbuild will have to do something like that.

[moltar]

@evanw thank you for your in-depth explanation! I really appreciate all of the effort and community management you put into this. 🙌🏼

Shall we close this in favor of #532 then?

[evanw]

Sure, sounds good. I greatly appreciate having a real-world example of this problem in practice though. So thank you very much for taking the time to put together a repro.

[evanw]

Closing in favor of #532.

[evanw]

I believe this should be working now as of version 0.8.55. Please let me know if that's not the case.

[moltar]

That does indeed fix the issue! Thank you so much for fixing this so quickly!