Support Bun by adjusting how @babel/plugin-transform-react-jsx is imported.

[paperdave]

Changes

This brings Astro a step closer to running on Bun by working around an existing workaround done when loading @babel/plugin-transform-react-jsx.

In Bun and some other tooling, importing a CommonJS module that has module.exports.__esModule will tell the module loader/bundler to set module.exports.default as the ESM default export, where without this annotation the default export will be set to module.exports. Node does not do this transformation, which turns transpiled-to-cjs modules like @babel/plugin-transform-react-jsx into { default: { default: Function } }, where in bun this loads as originally intended like { default: Function }

This PR fixes the three places astro uses .default.default and ensures it handles the case where it may be just .default.

Our tracking issue for Astro as a whole is oven-sh/bun#3746. This PR doesn't fully close that yet, as there are some remaining stability issues in Bun (random segfaults) when using larger projects.

Testing

I have been manually testing this on the astro.build docs locally on macos with node.js v20.5.0 and a development build of bun.

Docs

This is an internal change to the codebase and has no user-facing side effects. Maybe I should've added a comment for future code readers to understand why checking both .default.default and .default is necessary.

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[matthewp]

I'm not sure if we should add special-casing code for Bun. I could see someone looking at this code and thinking it's unnecessary and removing it.

[natemoo-re]

I'm not sure if we should add special-casing code for Bun. I could see someone looking at this code and thinking it's unnecessary and removing it.

I don't mind this change, personally! It seems trivial to support Bun's divergent behavior here. Since the ultimate goal for Bun is full Node compat, the rest of compatability issues will be their responsibility.

[natemoo-re]

LGTM. Worth noting that this code is changing in #7924 for 3.0, but this is worth merging regardless IMO!