Unhelpful startup error when nothing is passed to `--reporter` flag

Describe the bug

Running Vitest with --reporter but without a reporter name

vitest --reporter

results in an internal-looking error:

Error: Failed to load custom Reporter from true
...
[cause]: Error: Failed to convert JavaScript value `Boolean true` into rust type `String`
...

An error message like this would be more helpful:

Error: The --reporter option requires a reporter name.
Available examples: verbose, dot, json

Reproduction

https://stackblitz.com/edit/vitest-dev-vitest-nvlgtsbv?file=README.md&file=md!README.md&initialPath=__vitest__/

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 22.22.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.8.2 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    @vitest/ui: latest => 4.1.11 
    vite: latest => 8.2.1 
    vitest: latest => 4.1.11

Used Package Manager

npm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start by running vitest --reporter and tracing how the CLI parses the --reporter option before it attempts to load a custom reporter. Locate the related option handling and reporter tests, then verify that the command reports a clear missing-name error while valid reporter names continue to work.