We have flakey tests that give the error TypeError: Cannot read property 'createEvent' of null. Reading other SO questions, this indicates tests which finished before async calls had returned. I imagine it's some async issues or not mocking api calls, but it's proving impossible to debug because locally it only occurs intermittently (though frequently) and no information is given about which test or suite is failing.
A red fail number will appear in the status, but no message, and leaving it running, the tests will successfully complete with the failures disappeared. (It fails on our CI though). Any tips would be much appreciated!