Improve the error handling situation (#71)

* Sketches of a condition system

* `Condition.condition` -> `Condition.t`

* Migrate `NT` over

* Migrate `Branch` over

* Migrate `Sublanguage` et al. over

* Migrate the PRL over

* Migrate the DRL over

* Migrate the DML over

* Have `Qualified_name.try_parse` return a `Condition.t`

* Migrate the DDL over

* Migrate the VCL over

* Migrate the SCL over

* Migrate the ICL over

* Migrate the parsers over

* Just inherit the errors from NT and the sublanguages

* Migrate `Management.Physical` over

* Migrate `Configuration` over

* Migrate `Management.Branch` over

* Migrate `Transport` over

* Migrate `System` over

* Migrate `Server` over

* Include messages on on all conditions

* A prettier stringifier

1 files changed, 8 insertions, 2 deletions

diff --git a/lib/qualified_name.ml b/lib/qualified_name.ml
index 47134c8..a67f815 100644
--- a/lib/qualified_name.ml
+++ b/lib/qualified_name.ml
@@ -13,6 +13,12 @@
 
 type t = { mg : string; name : string }
 
+module Error = struct
+  open Condition
+  let unqualified_name name = condition "unqualified-name" "A qualified name was expected, but an unqualified one was given"
+                                ("name" |=| (of_string name))
+end
+
 exception Unqualified of string
 
 let parse (s : string) : t =
@@ -24,8 +30,8 @@ let parse (s : string) : t =
       if mg = "" || name = "" then raise (Unqualified s)
       else { mg; name }
 
-let try_parse (s : string) : (t, string) result =
-  try Ok (parse s) with Unqualified s -> Error s
+let try_parse (s : string) : (t, Condition.t) result =
+  try Ok (parse s) with Unqualified s -> Error (Error.unqualified_name s)
 
 let make ~mg ~name = { mg; name }