Do not clear input when switching between languages

### Clear and concise description of the problem Sometimes switch language only because I didn't notice the language is incorrect. ### Suggested solution Only clear input if the input is empty or example code. ### Alternative _No response_ ### Additional context _No response_ ### Validations - [x] Follow our [Code of Conduct](https://github.com/sxzz/.github/blob/main/CODE_OF_CONDUCT.md) - [x] Read the [Contributing Guide](https://github.com/sxzz/contribute). - [x] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.