Steps to reproduce problem:

1. Edit https://www.mediawiki.org/wiki/Git/Commit_message_guidelines in VisualEditor
2. Add some text
3. "Review and save"
4. "Something is wrong"
5. "Report problem"

Expected behaviour:
Make an http request somewhere and report back in the UI.

Actual behaviour:
No http request is made and UI is unresponsive.

console:

Uncaught TypeError: Converting circular structure to JSON
at:

mw.Target.prototype.reportProblem = function(message) {
var ...., report = { title: .., oldid: .., .. };
$.post(mw.config.get('wgVisualEditorConfig').reportProblemURL, {'data': JSON.stringify(report)}, function() {

debug:

var objs = [];
JSON.stringify(a, function (k, v) {

var i;
if (v === Object(v)) {
  i = objs.indexOf(v);
  if (i !== -1) {
    console.log('dupe at #' + i, v);
  }
  objs.push(v);
}
return v;

});
dupe at #66
<p data-parsoid=​"{"dsr":​[0,139,0,0]​}​">​
"The "
<b data-parsoid=​"{"tsr":​[4,7]​,"dsr":​[4,24,3,3]​}​">​commit message​</b>​
" play an important role in revision control systems. They are the first thing other people will see of your commit."
</p>​

Version: unspecified
Severity: critical