fix: always insert styled-vue-global-css

Author: egoist

lib/parseComponent.js

@@ -29,7 +29,8 @@ module.exports = (content, opts) => {
                   node.attrs[':style'] || node.attrs['v-bind:style']
                 node.attrs[':style'] = `$options.style(this, ${existing})`
               }
-              if (node.content && hasGlobalVars) {
+              if (hasGlobalVars) {
+                node.content = node.content || []
                 node.content.unshift({
                   tag: 'styled-vue-global-css'
                 })