Unfortunately go panics you try to cast a nil interface{} as another primitive
therefore you need to check interfaces are not nil before casting.
Fix#16025
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>