refactor

src/db.ml

@@ -34,3 +34,15 @@ let () =
   | Error _e ->
     Format.eprintf "db error@\n";
     exit 1
+
+let unwrap_err = function
+  | Error e -> Error (Format.sprintf "db error: %s" (Caqti_error.show e))
+  | Ok _ as ok -> ok
+
+let exec q v = Db.exec q v |> unwrap_err
+
+let find q v = Db.find q v |> unwrap_err
+
+let find_opt q v = Db.find_opt q v |> unwrap_err
+
+let collect_list q v = Db.collect_list q v |> unwrap_err