[Bug]: TypeError: Converting circular structure to JSON

[xiangechen]

Version

System:
    OS: macOS 26.1
    CPU: (12) arm64 Apple M2 Max
    Memory: 205.45 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
Browsers:
    Chrome: 142.0.7444.176
    Edge: 142.0.3595.94
    Safari: 26.1
npmPackages:
    @rstest/core: 0.6.8 => 0.6.8

Details

When a test fails, if there are circular references in the test object, serializing it to JSON will cause errors.

Reproduce link

https://github.com/xiangechen/rstest

Reproduce Steps

1. execute pnpm i
2. execute pnpm run test
3. find the error message in the console