Publishing source maps for @tailwindcss/upgrade

[bennycode]

I tried to upgrade from Tailwind v3 to v4 using @tailwindcss/upgrade. Unfortunately, the plugin crashes with the following error:

│ Migrating templates…

TypeError: Cannot read properties of undefined (reading 'flatMap')
at ca (file:///home/bennycode/.npm/_npx/0044b4041b3b52e1/node_modules/@tailwindcss/upgrade/dist/index.mjs:229:5661)

Since the package comes without source maps (https://www.npmjs.com/package/@tailwindcss/upgrade?activeTab=code), it is really hard to tell which line makes it crash.

The only usage of flatMap that I can see is here:

• https://github.com/tailwindlabs/tailwindcss/blob/v4.1.4/packages/%40tailwindcss-upgrade/src/utils/renderer.ts#L47

@RobinMalfait, @thecrypticace, @philipp-spiess: Is it possible to provide source maps?

Best,
Benny