Docusaurus: Validation error in themeConfig

[craigpalermo]

🐛 Bug Report

The new config validation reports that the following piece of configuration is invalid. However, it matches the documentation for syntax highlighting.

// docusaurus.config.js
module.exports = {
  // ...
  themeConfig: {
    prism: {
      additionalLanguages: ['kotlin', 'java'],
    },
    // ...
  },
};

Removing/commenting out the additionalLanguages line fixes the validation error.

To Reproduce

1. Run docusaurus start

Expected behavior

No validation error for valid configuration

Actual Behavior

A validation error occured.
The validation system was added recently to Docusaurus as an attempt to avoid user configuration errors.
We may have made some mistakes.
If you think your configuration is valid and should keep working, please open a bug report.

ValidationError: "prism.additionalLanguages" is not allowed

Your Environment

• Docusaurus version used: 2.0.0-alpha.61
• Environment name and version (e.g. Chrome 78.0.3904.108, Node.js 10.17.0): Node v12.18.1
• Operating system and version (desktop or mobile): MacOS 10.15.6

[teikjun]

Thanks! It's a mistake, I'll fix it