fix(models): if an image in wax is missing a src attribute, replace it with an empty paragraph
Closes #361 (closed) and #349 (closed)
Both issues are caused by buggy images. The editor content contains images where the source attribute is null, and that is not allowing the content to update
- in question version and complex item set models, parse the content for such buggy images and replace them an empty paragraph
- in the question page, check if such modification happened by comparing the result of the modification with the local input; if yes, trigger an rerendering of the editor to refresh the content