From 97c03df4ec0e46d9a2de34ba52fc6b1fd6b83340 Mon Sep 17 00:00:00 2001
From: ppokemon <86124405@qq.com>
Date: Thu, 23 May 2019 23:23:26 +0800
Subject: [PATCH] fix: Prevent input undefined

---
 index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.js b/index.js
index db48afc..5556893 100755
--- a/index.js
+++ b/index.js
@@ -33,7 +33,7 @@ module.exports = postcss.plugin('postcss-px-to-viewport', function (options) {
   return function (css) {
     css.walkRules(function (rule) {
       // Add exclude option to ignore some files like 'node_modules'
-      var file = rule.source.input.file;
+      var file = rule.source && rule.source.input.file;
 
       if (opts.exclude && file) {
         if (Object.prototype.toString.call(opts.exclude) === '[object RegExp]') {