BUG: Get approles results in error 500

When trying to run tests for Smart Home Security Server, I started getting error 500 from Auth.

Heroku logging spits out the following:

```
2020-10-01T15:00:03.600090+00:00 app[web.1]: Request: GET /approles/
2020-10-01T15:00:03.600090+00:00 app[web.1]: ** (exit) an exception was raised:
2020-10-01T15:00:03.600091+00:00 app[web.1]: ** (ArgumentError) session not fetched, call fetch_session/2
2020-10-01T15:00:03.600091+00:00 app[web.1]: (plug 1.10.4) lib/plug/conn.ex:1570: Plug.Conn.get_session/1
2020-10-01T15:00:03.600091+00:00 app[web.1]: (plug 1.10.4) lib/plug/conn.ex:1553: Plug.Conn.get_session/2
2020-10-01T15:00:03.600092+00:00 app[web.1]: (phoenix 1.5.4) lib/phoenix/controller.ex:1342: Phoenix.Controller.fetch_flash/2
2020-10-01T15:00:03.600092+00:00 app[web.1]: (auth 1.3.1) AuthWeb.Router.api/2
2020-10-01T15:00:03.600093+00:00 app[web.1]: (auth 1.3.1) lib/auth_web/router.ex:1: AuthWeb.Router.__pipe_through2__/1
2020-10-01T15:00:03.600093+00:00 app[web.1]: (phoenix 1.5.4) lib/phoenix/router.ex:347: Phoenix.Router.__call__/2
2020-10-01T15:00:03.600093+00:00 app[web.1]: (auth 1.3.1) lib/auth_web/endpoint.ex:1: AuthWeb.Endpoint.plug_builder_call/2
2020-10-01T15:00:03.600094+00:00 app[web.1]: (auth 1.3.1) lib/auth_web/endpoint.ex:1: AuthWeb.Endpoint.call/2
```

Start with the logged request to GET /approles/ and inspect AuthWeb.Router.api/2 in lib/auth_web/router.ex, then trace the Phoenix session and flash pipeline shown in the stack trace. Reproduce the request and identify why session access is reached without a fetched session. Done means the request no longer raises the reported error or returns HTTP 500.

Written by the indexing model from the issue text.