Error while collaborating on realtime document

While collaborating on a document having the following content:

{{velocity}}
#set($a = 1)
{{/velocity}}

|= XX |= YY
|(((
 Hi 

* List 1
* **List** 2
)))| Ho(((
* List 3
* Test
* List 4
* List 5
* List 6
* List 7
* List 8

(((
[[Link>>http://www.xwiki.com]]
)))
)))

Session was initiated by a computer on Chrome. A computer on Firefox joined and could not make changes:

The following error showed on the Firefox console

SyntaxError: An invalid or illegal string was specified
hyperscript.js
"ClassList(e).add(s)"

On the chrome compute the following error showed up:

Uncaught SyntaxError: Failed to execute 'add' on 'DOMTokenList': The token provided must not be empty.(anonymous function) @ hyperscript.js?cb=1458553090758:31forEach @ hyperscript.js?cb=1458553090758:145parseClass @ hyperscript.js?cb=1458553090758:25item @ hyperscript.js?cb=1458553090758:41h @ hyperscript.js?cb=1458553090758:120callOnHyperJSON @ hyperjson.js?cb=1458553090758:39(anonymous function) @ hyperjson.js?cb=1458553090758:25(anonymous function) @ prototype.js:8callOnHyperJSON @ hyperjson.js?cb=1458553090758:22applyHjson @ realtime-wysiwyg.js?cb=1458553090758:162config.onRemote @ realtime-wysiwyg.js?cb=1458553090758:173(anonymous function) @ realtime-cleartext.js?cb=1458553090758:264(anonymous function) @ realtime-cleartext.js?cb=1458553090758:131(anonymous function) @ reconnecting-websocket.js?cb=1458553090758:179ws.onmessage @ reconnecting-websocket.js?cb=1458553090758:278