I'd say there isn't really. A penalty is given because it is literally giving the attacking side the easiest possible means of scoring a goal. Given which, for a highly-paid professional whose main purpose is scoring goals to miss such an opportunity is very much professional negligence.
The universe doesn't really work like that though. Who knows what would have happened after that game?
The whole team and manager have been collectively at fault for the end of season collapse imo which has seen the St Totts drought extend into a third year.
And Bergkamp missed a big pelanty with dramatic consequences.
It most definitely is not. It may be a grave error, but professional negligence it most certainly isn't.
For a footballer to be guilty of professional negligence, he would need to fail to turn up on time for kick off. Once he is on the pitch he is performing tasks which, by their very nature, are prone to failure. If they were not, every game would finish 0-0.