Incorrect display of shorthand empty tags in the editor about zing

[iafan]

This is what happens:

1. We get the editor row as HTML. This HTML contains a <script>....</script> tag that initializes the editor.
2. We render this HTML in a container using jQuery html() method.
3. In html() method, jQuery explicitly tests if the passed HTML string contains certain tags, like <script>, <style>, or <link>. If any of these are found, it uses this.empty().append( value ); logic instead of native elem.innerHTML = value;.
4. jQuery.append() internally calls jQuery.buildFragment() from the given HTML string, and this is where (likely in this code) the resulting string inside embedded JS code gets rewritten (<Error /> is replaced with <Error ></Error>).

The code accidentally worked in the past because the to_js template filter would do double escaping and then pass through a runtime JSON.parse() call. Now that we don't do this kind of escaping, we need to deal with this specific case.

The ultimate fix would be to get rid of this whole HTML editor row snippet and script inside this snippet (by e.g. using a proper React component). meanwhile, a short-term workaround can probably be to make sure the rendered JavaScript strings inside editor row initialization code don't match this regular expression.

I'll PR a change for this fix shortly.

[julen]

Verified on my side, GTM 👍.