fix: hoistedTags may not always be present (close #35)

Author: yyx990803

lib/webpack/markdownLoader.js

@@ -78,7 +78,7 @@ module.exports = function (src) {
     `<template>\n` +
       `<div class="content">${html}</div>\n` +
     `</template>\n` +
-    hoistedTags.join('\n')
+    (hoistedTags || []).join('\n')
   )
   cache.set(key, res)
   return res