genEnum crashes on empty group

[Soupstraw]

Description

genEnum crashes when given an empty group because choose receives an invalid range.

Location

src/Codec/CBOR/Cuddle/CBOR/Gen.hs, genEnum function

Details

genEnum tree = case tree of
  CTree.Group trees -> do
    ix <- choose (0, length trees - 1)
    genForCTree $ trees !! ix

When trees is empty, choose (0, length trees - 1) becomes choose (0, -1), which is an invalid range.

Suggested fix

Handle empty groups explicitly with a clear error message before calling choose.