be able to output little prefix strings on failed assertion / comments

[berndbischl]

sometimes it is really need to inform the the user WHY you are enforcing a certain thing.

i would love to be able to do this

asssertFactor(f, na.ok = FALSE, comment = "'f' shouldnt be NA because bla")

and "comment" is pasted directly before the failed assertion error message.

that would be super useful in many cases to make user feedback better

[PetterHopp]

I support the idea of the possibility to include a comment if the assertation fails. This can be very useful in aiding the user in how to correct their arguments to the functions. However, I will prefer to have the comment pasted directly after the "standard" message. Then you keep the well-considered way checkmate presents the error messages and the comment is used to explain and help the user.