When a function has no spec, assume function type with any() args and…

… return type

Even when a function does not have a spec, we still know that it is a function
and that is of certain arity.

This is probably related to making the infer flag default in josefs#573, as without
infer, we always assumed any() when there wasn't a spec for something.

src/typechecker.erl

@@ -5798,7 +5798,7 @@ create_fenv(Specs, Funs) ->
 % case it will mean that if there is a spec, then that will take precedence
 % over the default type any().
     maps:from_list(
-      [ {{Name, NArgs}, [type(any)]}
+      [ {{Name, NArgs}, absform:normalize_function_type_list([type_fun(NArgs)])}
         || {function,_, Name, NArgs, _Clauses} <- Funs
       ] ++
       [ {{Name, NArgs}, absform:normalize_function_type_list(Types)}