Browser mode: unable to mock modules from workspace projects

[jrobinson01]

Describe the bug

When using npm workspaces and attempting to mock a module from an adjacent workspace project, vitest in browser mode silently fails to mock modules from other projects in the same workspace. Running the tests with the vitest defaults works as expected.

Reproduction

https://github.com/jrobinson01/vitest-browser-workspace-mocks-issue
install deps then cd into package-a and run npm run test to run the test using vitest. Tests should pass. Run npm run test:browser and observe the failing test.

System Info

System:
    OS: macOS 14.7.3
    CPU: (12) arm64 Apple M2 Pro
    Memory: 568.36 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.15.0 - ~/.nvm/versions/node/v20.15.0/bin/node
    Yarn: 1.22.22 - ~/.yarn/bin/yarn
    npm: 10.7.0 - ~/.nvm/versions/node/v20.15.0/bin/npm
  Browsers:
    Chrome: 132.0.6834.160
    Chrome Canary: 134.0.6996.0
    Safari: 18.3

Used Package Manager

npm

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