Network Error without a status code

[sentry]

We're unable to see the response status code, and determine the root cause.

Sentry Issue: STUDIO-FMD

Error: Network Error: /api/sync/
  at Error: Network Error:  (/api/sync/)
  at callback (./shared/client.js:65:33)
  at <anonymous> (./shared/client.js:59:7)
  at None (async https://studio.learningequality.org/static/studio/channel_edit-96b105a391f59bf1d576.js:8:3135951)
...
(1 additional frame(s) were not displayed)

[bjester]

Possibly connected to axios/axios#4655

[bjester]

Addressed in #3855