From 8bc6986cacb7c5d64c62aef0dd801cb0b99daa4a Mon Sep 17 00:00:00 2001
From: eight <eight04@gmail.com>
Date: Tue, 12 Sep 2017 00:08:54 +0800
Subject: [PATCH] Change: make unknown preprocessor throw

---
 js/usercss.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/js/usercss.js b/js/usercss.js
index 7c5835b0..5099e8b0 100644
--- a/js/usercss.js
+++ b/js/usercss.js
@@ -203,7 +203,10 @@ var usercss = (function () {
 
   function buildCode(style) {
     let builder;
-    if (style.preprocessor && style.preprocessor in BUILDER) {
+    if (style.preprocessor) {
+      if (!BUILDER.hasOwnProperty(style.preprocessor)) {
+        return Promise.reject(new Error(`Unsupported preprocessor: ${style.preprocessor}`));
+      }
       builder = BUILDER[style.preprocessor];
     } else {
       builder = BUILDER.default;