module Error:sig..end
Handling errors.
Internal module holding the exception of Error.
The module is included into Make_with_opt later and should not be used
directly. However we need to have a separate module for the exception so
that every exception built by Make is the exact same type.
module type S =sig..end
module Make:
Functor to build an Error module for a given phase.
include Error.S
The Error module implements Error.S with no phase.