L0 typechecking errors, matching names but differing numbers

[jazullo]

Consider this code
This results in the following error:

~/gibbon$ cabal v2-exec gibbon -- --packed --no-gc --to-exe ../llrbt/break.hs
gibbon: lookupDataCon: could not find constructor "Nil_v_236", in datatypes:
  [(Maybe,
  DDef {tyName = "Maybe",
        tyArgs = [b:a_26],
        dataCons = [("Just", [(False, TyVar b:a_26)]),("Nothing", [])]}),
 (PList,
  DDef {tyName = "PList",
        tyArgs = [b:a_27],
        dataCons = [("Nil", []),
                    ("Cons",
                     [(False, TyVar b:a_27),
                      (False, PackedTy "PList" [TyVar b:a_27])])]}),
 (PList_v_239,
  DDef {tyName = "PList_v_239",
        tyArgs = [],
        dataCons = [("Nil_v_239", []),
                    ("Cons_v_239",
                     [(False, PackedTy "Maybe_v_235" []),
                      (False, PackedTy "PList_v_239" [])])]}),
 (PList_v_237,
  DDef {tyName = "PList_v_237",
        tyArgs = [],
        dataCons = [("Nil_v_237", []),
                    ("Cons_v_237",
                     [(False, PackedTy "Maybe" [IntTy]),
                      (False, PackedTy "PList_v_237" [])])]}),
 (Maybe_v_235,
  DDef {tyName = "Maybe_v_235",
        tyArgs = [],
        dataCons = [("Just_v_235", [(False, IntTy)]),
                    ("Nothing_v_235", [])]})]
CallStack (from HasCallStack):
  error, called at src/Gibbon/Language/Syntax.hs:149:11 in gibbon-0.2-inplace:Gibbon.Language.Syntax

There is a Nil defined, but for some reason it is differentiated from the sought-after Nil.
When commenting out the active line in the main function and replacing it with the line below, a similar-but-different type checking error is produced instead:

~/gibbon$ cabal v2-exec gibbon -- --packed --no-gc --to-exe ../llrbt/break.hs
gibbon: L0.Typecheck:
    Couldn't match type 'PackedTy "PList_v_232"
                                  []' with 'PackedTy "PList_v_235" []'
    Expected type: PackedTy "PList_v_235" []
    Actual type: PackedTy "PList_v_232" []
    In the expression:
      AppE "fold_plist_233"
           []
           [Ext (FunRefE [] "alt_maybe_230"),
            DataConE (ProdTy []) "Nothing_v_231" [],
            DataConE (ProdTy []) "Nil_v_232" []]
CallStack (from HasCallStack):
  error, called at src/Gibbon/L0/Typecheck.hs:66:32 in gibbon-0.2-inplace:Gibbon.L0.Typecheck

These functions are able to typecheck in translations to OCaml