Move column increment to decodeField

lib/Database/PostgreSQL/Opium.hs

@@ -131,9 +131,8 @@ instance FromRow' f => FromRow' (M1 C c f) where
   fromRow' ctx row = M1 <$> fromRow' ctx row
 
 instance (FromRow' f, FromRow' g) => FromRow' (f :*: g) where
-  fromRow' ctx@(FromRowCtx _ _ iRef) row = do
+  fromRow' ctx row = do
     y <- fromRow' ctx row
-    liftIO $ modifyIORef' iRef (+1)
     z <- fromRow' ctx row
     pure $ y :*: z
 
@@ -146,6 +145,7 @@ decodeField
   -> ExceptT Error IO (M1 S m (Rec0 t') p)
 decodeField nameText g (FromRowCtx result columnTable iRef) row = do
   i <- liftIO $ readIORef iRef
+  liftIO $ modifyIORef' iRef (+1)
   let (column, oid) = columnTable `indexColumnTable` i
   mbField <- liftIO $ getFieldText column
   mbValue <- except $ getValue oid mbField