[Bug]: Failed to get stats when compiling MF exposed entrypoint

[jbroma]

System Info

 System:
    OS: macOS 15.1.1
    CPU: (10) arm64 Apple M1 Pro
    Memory: 4.65 GB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.13.1 - ~/Library/Caches/fnm_multishells/46674_1736250537490/bin/node
    npm: 10.5.2 - ~/Library/Caches/fnm_multishells/46674_1736250537490/bin/npm
    pnpm: 9.15.3 - ~/Library/Caches/fnm_multishells/46674_1736250537490/bin/pnpm
    bun: 1.1.34 - /opt/homebrew/bin/bun
    Watchman: 2024.11.04.00 - /opt/homebrew/bin/watchman
  Browsers:
    Chrome: 131.0.6778.205
    Safari: 18.1.1
  npmPackages:
    @rspack/core: ^1.1.8 => 1.1.8

Details

During compilation of a MF remote entrypoint the following warning is emitted:

Failed to get stats. Are you trying to access the stats from the previous compilation?

which means that the result of stats.toJson() is set to null. TS definitions don't include the null result of stats.toJson() and therefore in Re.Pack this is not handled properly (similar case never occurs when using Webpack).

Related issue in Re.Pack: callstack/repack#854

Reproduce link

https://github.com/jbroma/repack-rspack-stats-repro

Reproduce Steps

1. Clone the repo
2. pnpm install
3. pnpm start

(more verbose instructions in the repo README.md)

[jbroma]

It seems like the compiler shuts down on the Rust side, but continues to execute normally on the JS side. I'm not able to pinpoint this to anything on the Rust side, is there any way to debug this with the release version of Rspack?

[h-a-n-a]

I debugged into the source code and found out this might be an error related to the callsite plugin:

We will add more context to the error message.

[jbroma]

I debugged into the source code and found out this might be an error related to the callsite plugin:

We will add more context to the error message.

Thank you so much for your help @h-a-n-a - only now I've realised you've already provided enough info to fix this on Re.Pack side!

If you have any guidance on how you would like to implement more verbose error message for the future in Rspack, I'll be happy to take that and contribute to Rspack 🙏