Interesting find this evening,
I copied a snip of text to use as documentation in my patch and when trying to save the patch I receive the error message;
An error of type type-error occurred: #\" (of type character) is
not of type base-char.
I thought, interesting. I went through and started to remove bits of the copied text line by line, saving after each removal to find these two fellows as the culprits
“ ”
This would be the inverted quotation mark?
Of course, my keyboard would normally just type
" and "
and as such the problem is easily rectified.
Just thought I would share as the only other mention I have seen of a character incompatibility is with non-latin characters.