apport apport-collect "coding exception"

while trying to update a bug report
apport-collect -p xorg 1424864

A coding exception was thrown and uncaught in a Task.

Full message: TypeError: f.readTo is not a function
...
Full stack: exports.IO.readFromFile/<@resource://gre/modules/addons/XPIProvider.jsm -> jar:file:///home/xxx/.mozilla/firefox/xxxx.default/extensions/%7Bd10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d%7D.xpi!/bootstrap.js -> jar:file:///home/xxx/.mozilla/firefox/xxx.default/extensions/%7Bd10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d%7D.xpi!/lib/io.js:207:28
TaskImpl_run@resource://gre/modules/Task.jsm:330:41
Handler.prototype.process@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:870:23
this.PromiseWalker.walkerLoop@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:749:7
this.PromiseWalker.scheduleWalkerLoop/<@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:691:37