[COASTAL-1461] Completion handler called twice with delay

[nhamming]

https://tidepool.atlassian.net/browse/COASTAL-1461

Unfortunately, I'm not certain why the ASWebAuthenticationSession completion handler is being called twice. It seems to only occur when there is a network delay. The callback URL for the second call is as described in crashlytics:

... tried to resume its continuation more than once returning org.tidepool.tidepoolkit.auth://redirect?
error=temporarily_unavailable&error_description=authentication_expired&iss=https%3A%2F%2Fauth.qa2.tidepool.org
%2Frealms%2Fqa1!

This stops the crash, but obviously does not fix the root issue.

[ps2]

LGTM!