[IGN-16327]Small bug in new system.db.exec* functions?

Noticed recently with the system.db.exec* functions for named queries, that if you mistype the named query path, it gives a crappy error.

It tells you that your parameters are wrong: Parameter mismatch. Expected: , but provided: [meterid]

When in reality, the Named Query you're calling doesn't exist.

Thanks for the report. In attempting to replicate, I ended up running into some NPEs that we'll also have to fix, but we'll get it all done simultaneously.