* Handle invalid issues
- When you hover over a issue reference, and the issue doesn't exist, it
will just hang on the loading animation.
- This patch fixes that by showing them the pop-up with a "Error
occured" message.
* Add I18N
* refactor
* fix comment for lint
* fix unit test for i18n
* fix unit test for i18n
* add comments
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>