* Propagate errors in tls_config instead of unwrap
Ran into `tls_connector` failing and causing our app to panic and shutdown as it seems there wasn't any way to avoid panicking in `tls_config`.
So after talking to @LucioFranco briefly `tls_config` now returns a `Result` instead and propagates errors to the caller, where they can be handled.
* Fix compile warning when tls feature is disabled
