According to the content schema, parts of a guide are optional. This would mean a guide could have no content and that seems wrong.

When I first tested this on 20 Apr, I had problems previewing content:

1. Remove a single part from a guide
2. Save
3. Try to preview

This preview failed and the draft stack told me "Page not found" I also tried the same but publishing at the end, also "Page not found".

During this time, when I removed all parts from a guide and hit save, the page told me the guide had saved successfully, and when coming back to it I could see there were no parts in the document.

Today, Apr 21, I tried this again to see if preview was working. Following the same steps I could see that removing a single part and saving, that parts was removed and I could see the draft on the draft stack.

However – when I tried to remove all parts the application responded differently. The form would not save, the inspector showed me that the POST request to remove all parts was 404ing.