[FTypeChecker] More informative error message (and more robust code) when typechecking variants. #64
In some cases, a [Not_found] exception is raised, for instance when a label cannot be found inside a given type declaration or if a type declaration cannot be found (see [typeof_variant]).
Deleting a branch is permanent. Although the deleted branch may exist for a short time before cleaning up, in most cases it CANNOT be undone. Continue?