Idris node codegen bug (Can't happen pickAlt - impossible case found)

Main.idr

import IdrisScript

Schema : Type
Schema = List (String, Type)

-- First class record
data Record : Schema -> Type where
  RecNil : Record Nil
  RecCons : (key:String) -> (val : t) -> Record lst -> Record ((key, t)::lst)

data Useless : Type where I : Useless

-- The type at the given key in a schema
typeAtKey : Schema -> String -> Type
typeAtKey Nil _ = Useless
typeAtKey ((k', t)::rest) k = if (k' == k) then t else (typeAtKey rest k)

-- Access a field of a record
access : Record keyMap -> (k : String) -> typeAtKey keyMap k
access RecNil k = I
access (RecCons key val rest) k with (key == k)
  | True = val
  | False = access rest k

refToRecords : JSRef -> JS_IO (Maybe (Int))
refToRecords ref = do
  packed <- pack ref
  pure Nothing

toRecord : Record [("rows", JSRef)] -> JS_IO Int
toRecord rec = believe_me (refToRecords (access rec "rows")) 

mapIO : (a -> JS_IO b) -> JS_IO (Maybe a) -> JS_IO (Maybe b)
mapIO f ev = ev >>= (believe_me () . map f)

runSelectQuery : JS_IO (JS_IO (Maybe (Int)))
runSelectQuery = pure (mapIO toRecord (believe_me ()))
      
main : JS_IO ()
main = do
  runSelectQuery
  pure ()