come mai this.$refs.container non esiste?

src/components/Viewer/Viewer.vue

@@ -209,8 +209,10 @@ export default {
     this.$refs.iframe.appendStyle(this.$options.rotateWrapperStyle)
     // TODO: element resize replace window resize with Observe
     this.handleResize = throttle(() => {
+    try{
       this.viewportHeight = this.$refs.container.clientHeight
       this.viewportWidth = this.$refs.viewerScroller.clientWidth
+    }catch(e){}
     }, 100)
 
     window.addEventListener('resize', this.handleResize)