Bug in adding articles in sale application (more than available in stock) + error message

[JornHendrickx]

bug: there was only 1 codex in the system, so with the add article button (f5) I could add that 1 codex, but after that I could keep adding codices
(maybe this has to do with the fact that the codex is a common article?)

possible adjustment: when trying to add an article (of which there were not enough in stock), an error is displayed -> this is expected behavior, because there were not enough in stock, but can the error be more intelligible?