TypeError when moving away from an element before a classification was created

Sentry Issue: ARKINDEX-FRONTEND-AYB

TypeError: this.$refs.newClassificationSelect is null
  at Vu.methods.createClassification (./src/components/Element/DetailsPanel.vue:176:9)

1. Open an element.
2. Once everything has loaded, open the dev tools and restrict the network bandwidth to something horrible like GPRS. Alternatively, edit your backend to add a time.sleep(5) in CreateClassification.
3. Create a classification on that element.
4. Switch to another page before the classification creation ends.
5. Get TypeError'd.
6. Cry.