Parse errors on deriving clauses a class itself causes a crash

[anka-213]

I was trying to add deriving to all my data types with a naive regex which caused the following code:

record Example : Set where
{-# COMPILE AGDA2HS Example deriving (Show, Eq, Ord) class #-}

Trying to run agda2hs on it gives the following error:

$ agda2hs Bug.agda
Checking Bug (Bug.agda).
An internal error has occurred. Please report this as a bug.
Location of the error: __IMPOSSIBLE__, called at src/full/Agda/Utils/FileName.hs:56:20 in Agda-2.6.4.1-7xG50m7UQLK4krJEY6TPg:Agda.Utils.FileName

Not that anyone should do this, but the error message said it's a bug, so I might as well report it so mistakes like these can get better error messages.