fix: test command

[thejackshelton]

What:
This PR fixes a type error that is shown in CI. It previously had a ts-expect-error comment above, but CI blocks you from being able to run the test or setup script following the README.md file.

I would like to contribute to this package and ensure that the tests added going forward are working 🙂

Why:
Without this change, we are unable to run the tests or other scripts, at least not on the environment and node version I am using (v22.14)

How:
I looked at a couple of posts online regarding this issue, which seems to be notorious. The solution uses Object.defineProperty to properly handle the getter-only navigator property, which seems to be the preferred JavaScript solution for this type of issue.

Checklist:

• Documentation
• Tests
• Ready to be merged

I believe so, but happy to discuss what might be a better approach

Issue stack trace:

jackshelton@MacBook-Pro mdx-bundler % npm run setup -s
[test] TypeError: Cannot set property navigator of #<Object> which has only a getter
[test]     at file:///Users/jackshelton/dev/open-source/mdx-bundler/src/__tests__/setup-tests.js:23:18
[test]     at ModuleJob.run (node:internal/modules/esm/module_job:271:25)
[test]     at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:578:26)
[test]     at async Module.run (file:///Users/jackshelton/dev/open-source/mdx-bundler/node_modules/uvu/run/index.mjs:9:3)
[test]     at async /Users/jackshelton/dev/open-source/mdx-bundler/node_modules/uvu/bin.js:26:5
[test] ------------|---------|----------|---------|---------|-------------------
[test] File        | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
[test] ------------|---------|----------|---------|---------|-------------------
[test] All files   |   74.52 |      100 |       0 |   74.52 |                   
[test]  src        |   75.08 |      100 |       0 |   75.08 |                   
[test]   index.js  |   75.08 |      100 |       0 |   75.08 | 36-48,56-112      
[test]  src/client |   69.69 |      100 |       0 |   69.69 |                   
[test]   jsx.js    |   69.69 |      100 |       0 |   69.69 | 12-15,26-31       
[test] ------------|---------|----------|---------|---------|-------------------
[test] npm run test --silent -- --coverage exited with code 1
--> Sending SIGTERM to other processes..
[lint] npm run lint --silent exited with code SIGTERM
--> Sending SIGTERM to other processes..
[typecheck] npm run typecheck --silent exited with code SIGTERM
--> Sending SIGTERM to other processes..
[build] npm run build --silent exited with code SIGTERM
jackshelton@MacBook-Pro mdx-bundler % 

envinfo:

  System:
    OS: macOS 15.1
    CPU: (16) arm64 Apple M4 Max
    Memory: 7.58 GB / 48.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.14.0 - ~/.nvm/versions/node/v22.14.0/bin/node
    Yarn: 1.22.22 - /usr/local/bin/yarn
    npm: 10.9.2 - ~/.nvm/versions/node/v22.14.0/bin/npm
    pnpm: 10.7.0 - ~/.nvm/versions/node/v22.14.0/bin/pnpm
    bun: 1.1.7 - ~/.bun/bin/bun
  Managers:
    Cargo: 1.85.0 - ~/.cargo/bin/cargo
    Homebrew: 4.4.24 - /opt/homebrew/bin/brew
    pip3: 24.3.1 - /opt/homebrew/bin/pip3
    RubyGems: 3.0.3.1 - /usr/bin/gem
  Utilities:
    Make: 3.81 - /usr/bin/make
    GCC: 16.0.0 - /usr/bin/gcc
    Git: 2.39.5 - /usr/bin/git
    Clang: 16.0.0 - /usr/bin/clang
    FFmpeg: 7.1 - /opt/homebrew/bin/ffmpeg
    Curl: 8.7.1 - /usr/bin/curl
    OpenSSL: 3.4.0 - /opt/homebrew/bin/openssl
  Servers:
    Apache: 2.4.62 - /usr/sbin/apachectl
  Virtualization:
    Docker: 28.0.1 - /opt/homebrew/bin/docker
    Docker Compose: 2.33.1 - /opt/homebrew/bin/docker-compose
  SDKs:
    iOS SDK:
      Platforms: DriverKit 24.2, iOS 18.2, macOS 15.2, tvOS 18.2, visionOS 2.2, watchOS 11.2
  IDEs:
    Android Studio: 2024.2 AI-242.23339.11.2421.12700392
    VSCode: 0.48.2 - /usr/local/bin/code
    Vim: 9.0 - /usr/bin/vim
    Xcode: 16.2/16C5032a - /usr/bin/xcodebuild
  Languages:
    Bash: 3.2.57 - /bin/bash
    Perl: 5.34.1 - /usr/bin/perl
    Python3: 3.13.1 - /opt/homebrew/bin/python3
    Ruby: 2.6.10 - /usr/bin/ruby
    Rust: 1.85.0 - /Users/jackshelton/.cargo/bin/rustc
  Databases:
    SQLite: 3.43.2 - /usr/bin/sqlite3
  Browsers:
    Brave Browser: 127.1.68.141
    Chrome: 134.0.6998.166
    Safari: 18.1

[thejackshelton]

succeeded by #240