[json] Remove JSON module altogether

src/main.ml

@@ -182,7 +182,7 @@ let record_verification_result verification_result file =
     verification_result
 
 let verify_json ?memlimit ?timelimit ?outfile json =
-  let query = Json.to_query json in
+  let query = Verification_types.Query.of_json json in
   let query =
     (* Precedence to the command line option, if any. *)
     (* TODO: * get proper default value instead of defining it twice in

src/verification_types.ml

@@ -93,6 +93,16 @@ module Query = struct
       dataset;
     }
 
+  let of_json s =
+    match of_yojson (Yojson.Safe.from_file s) with
+    | Ok t -> t
+    | Error msg ->
+      invalid_arg
+        (Fmt.str "Unrecognized JSON configuration in file '%s' (%s)" s msg)
+    | exception Yojson.Json_error msg ->
+      failwith
+        (Fmt.str "Unexpected error while parsing JSON file '%s' (%s)" s msg)
+
   let pretty fmt = Fmt.fmt "%a" fmt pp
 end