Addition for #8
User perspective
Some values for spelling_language cannot be parsed and therefore also no validation of the LanguageTag can be performed. This Pull Request adds that in such cases the validation (as part of the check command) also detects an invalid value.
Developer perspective
See commit messages for some details.
Addition for #8
### User perspective
Some values for `spelling_language` cannot be parsed and therefore also no validation of the `LanguageTag` can be performed. This Pull Request adds that in such cases the validation (as part of the `check` command) also detects an invalid value.
### Developer perspective
See commit messages for some details.