The problem with this is that it would have to be an entirely different entity than the forum itself. A lot of forum errors may result from not being able to connect to the database, for example. If this is the case, the error message wouldn't be displayed unless it was placed in an entirely separate database which was not effected. Also, let's say, for example, there was an error in the header or initial opening scripts of the board.
I'll move this to the MOD requests forum for now. They're a lot more skilled with coming up with ways to do things than I am.