fix: Set ffIsEnabled only auth provider is present in config
Created by: KattMingMing
Resolves: https://github.com/sourcegraph/sourcegraph/issues/1785
When only 1 OAuth provider was enabled at a time there was an issue that the wrong provider was returned. This error surfaced because of the use of getExactlyOneOAuthProvider call which would attempt to redirect to the externalURL
.
I confirmed this works for:
- 1 OAuth provider (auto-redirect still works)
- built-in + 1 OAuth
- built-in + 2 OAuth
- 2 OAuth