[Bug]: No error on missing project in UI Mode

[agg23]

Version

1.50.0

Steps to reproduce

1. Take any Playwright setup
2. Run npx playwright test --project=foo --ui

Expected behavior

This should throw an error that project "foo" doesn't exist. An error is thrown when running npx playwright test --project=foo.

Actual behavior

UI mode opens as normal, and can't find any tests because the project doesn't exist.

Additional context

No response

Environment

System:
    OS: macOS 15.2
    CPU: (12) arm64 Apple M4 Pro
    Memory: 128.98 MB / 24.00 GB
  Binaries:
    Node: 22.12.0 - ~/.nvm/versions/node/v22.12.0/bin/node
    npm: 11.0.0 - ~/.nvm/versions/node/v22.12.0/bin/npm
  IDEs:
    VSCode: 1.96.3 - /opt/homebrew/bin/code
  Languages:
    Bash: 3.2.57 - /bin/bash