better lines_of_input error

src/utils.ml

@@ -2,7 +2,7 @@ let lines_of_input day =
   let base_path =
     match Inputs.Sites.inputs with
     | path :: _ -> path
-    | _ -> failwith "cant find sites path"
+    | _ -> failwith "cant find path containing inputs"
   in
   let path = Printf.sprintf "%s/day%d.tt" base_path day in
   Stdio.In_channel.(with_file path ~f:input_lines)