Frequent 'Application error' on Heroku

[rjjfox]

H10 error without clear indication of what is causing the error.

The sample size app is working fine. Restarting the app brings it back online but only temporarily.

`2020-12-02T17:55:31.600161+00:00 heroku[router]: at=info method=GET path="/static/js/35.8b5aee2e.chunk.js" host=abtestcalculator.herokuapp.com request_id=6bed4e59-39e6-4eb4-91ba-054177676381 fwd="86.26.169.205" dyno=web.1 connect=7ms service=713ms status=200 bytes=924 protocol=https
2020-12-02T17:55:32.004219+00:00 heroku[router]: at=info method=GET path="/stream" host=abtestcalculator.herokuapp.com request_id=a07d1d46-eeb0-4f56-b346-372e71abaa39 fwd="86.26.169.205" dyno=web.1 connect=3ms service=7089ms status=101 bytes=3704 protocol=https
2020-12-02T18:31:56.360217+00:00 heroku[web.1]: Idling
2020-12-02T18:31:56.362124+00:00 heroku[web.1]: State changed from up to down
2020-12-02T18:31:57.289592+00:00 heroku[web.1]: Stopping all processes with SIGTERM
2020-12-02T18:31:57.326310+00:00 app[web.1]: Stopping...
2020-12-02T18:31:57.909981+00:00 heroku[web.1]: Process exited with status 0
2020-12-04T23:48:36.484998+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/robots.txt" host=testcalculator.rfoxdata.co.uk request_id=e6332438-f459-4454-95a5-da0723859f0a fwd="66.249.64.131" dyno= connect= service= status=503 bytes= protocol=http
2020-12-07T18:09:57.005798+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=abtestcalculator.herokuapp.com request_id=aec55d2e-2e73-4727-8198-5c0ec3939a5c fwd="86.26.169.205" dyno= connect= service= status=503 bytes= protocol=https
2020-12-07T18:09:57.810181+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=abtestcalculator.herokuapp.com request_id=5a18804b-5ad4-47e1-8da8-a846fec70f17 fwd="86.26.169.205" dyno= connect= service= status=503 bytes= protocol=https
2020-12-07T18:11:04.649913+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=abtestcalculator.herokuapp.com request_id=a056875b-5aec-4a03-8c46-abf380e81cff fwd="86.26.169.205" dyno= connect= service= status=503 bytes= protocol=https
2020-12-07T18:11:05.248761+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=abtestcalculator.herokuapp.com request_id=95adaa28-9ccd-46c2-aa61-317457945f65 fwd="86.26.169.205" dyno= connect= service= status=503 bytes= protocol=https`