Empty annotation can't be updated and Arender goes to infinite loading

Reproduction steps

1. Create a document
2. Go to annotation tab
3. create a freehand annotation
4. Wait for autosave
5. Go to annotation browser (section on the left)
6. double click on the freehand annotation text part
7. start typing some text in the field

Observed result

7. the submit button disappears and is replaced by reply

7. I can't save my changes 

7. The arender page loading endless

Expected result

7. The submit button remains until I click on it

7. My changes are saved

7. There is no endless loading