Simplify TlsListener::configure

Now that we no longer need to return the TlsAcceptor, integrate the
error handling into the preceeding match.

Author: joshtriplett

src/tls_listener.rs

@@ -86,17 +86,17 @@ impl<State> TlsListener<State> {
                 TlsListenerConfig::Acceptor(TlsAcceptor::from(Arc::new(config)))
             }
 
-            other => other,
+            other @ TlsListenerConfig::Acceptor(_) => other,
+
+            TlsListenerConfig::Unconfigured => {
+                return Err(io::Error::new(
+                    io::ErrorKind::Other,
+                    "could not configure tlslistener",
+                ));
+            }
         };
 
-        if let TlsListenerConfig::Acceptor(_) = self.config {
-            Ok(())
-        } else {
-            Err(io::Error::new(
-                io::ErrorKind::Other,
-                "could not configure tlslistener",
-            ))
-        }
+        Ok(())
     }
 
     fn acceptor(&self) -> Option<&TlsAcceptor> {