Add unit tests for existing front-end models

[Venefilyn]

Currently no tests exists for front-end models, tests need to be written for:

• [ ] Config.js
• [ ] ConfigData.js
• [ ] ConfigErrors.js
• [x] EmptyData.js
• [ ] ErrorData.js
• [ ] Guild.js
• [x] GuildChannel.js
• [x] GuildRole.js
• [ ] PublicGroup.js
• [x] BlankPublicGroup.js
• [ ] PublicRole.js