Describe the regression

React-moment (alongside setting resolve.mainFields) used to work until rolldown-vite 7.1.19

Reproduction

https://github.com/adhami3310/react-moment-rolldown-repro

Expected Behavior

It displays a date

Actual Behavior

It errors in the browser console with:

Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object.

Check the render method of `Component`.

Steps to Reproduce

bun install followed by bun run dev, although i verified npm has this problem as well

System Info

System:
    OS: Linux 6.17 Arch Linux
    CPU: (16) x64 AMD Ryzen 9 7940HS w/ Radeon 780M Graphics
    Memory: 47.53 GB / 58.66 GB
    Container: Yes
    Shell: 4.2.1 - /bin/fish
  Binaries:
    Node: 25.2.1 - /usr/bin/node
    npm: 11.6.3 - /usr/bin/npm
    bun: 1.3.2 - /usr/bin/bun
    Deno: 2.5.6 - /usr/bin/deno
  npmPackages:
    rolldown-vite:  7.2.7

Used Package Manager

bun

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs and the Rolldown-related guide.
• Check that there isn't already an issue that reports the same regression to avoid creating a duplicate.
• Check that this is a concrete regression. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the regression.