It's just an error message, it has no more significance than that. There are other error messages of course, this is just one of the most annoying.
I think if you did
hint format ["%1", var1]
you would get it, providing of course that var1 does not exist.
Why somebody would set a local variable to that value I cannot imagine. It sounds like the sort of thing you would do when you need some kind of random string, and you've been getting that error a lot.