Design discussion note preview is broken

Summary

On Design discussion, when adding a new comment, the Preview tab doesn't show a preview. Instead, an error is thrown to the console:

Screenshot_2020-02-03_at_16.11.30

Steps to reproduce

  1. Open Designs tab on the issue
  2. Upload a new design.
  3. Click on a design to enlarge it.
  4. Click on the enlarged design to start a new discussion.
  5. Add some text to the textarea.
  6. Click on Preview tab

What is the current bug behavior?

There is no preview and an error appears in the console

What is the expected correct behavior?

There should be a preview shown