Don't treat empty object as a valid sfu config

This was causing an extra reconnect cycle when the call was first
joined because it thought the previous SFU config was valid. This was
probably causing some client to fail to connect at all.

src/livekit/useECConnectionState.ts

@@ -36,6 +36,12 @@ export enum ECAddonConnectionState {
 
 export type ECConnectionState = ConnectionState | ECAddonConnectionState;
 
+// This is mostly necessary because an empty useRef is an empty object
+// which is truthy, so we can't just use Boolean(currentSFUConfig.current)
+function sfuConfigValid(sfuConfig?: SFUConfig): boolean {
+  return Boolean(sfuConfig?.url) && Boolean(sfuConfig?.jwt);
+}
+
 export function useECConnectionState(
   livekitRoom?: Room,
   sfuConfig?: SFUConfig
@@ -68,18 +74,22 @@ export function useECConnectionState(
 
   const currentSFUConfig = useRef(Object.assign({}, sfuConfig));
 
+  // Id we are transitioning from a valid config to another valid one, we need
+  // to explicitly switch focus
   useEffect(() => {
     if (
-      sfuConfig &&
+      sfuConfigValid(sfuConfig) &&
-      currentSFUConfig.current &&
+      sfuConfigValid(currentSFUConfig.current) &&
       !sfuConfigEquals(currentSFUConfig.current, sfuConfig)
     ) {
-      logger.info("JWT changed!");
+      logger.info(
+        `SFU config changed! URL was ${currentSFUConfig.current?.url} now ${sfuConfig?.url}`
+      );
 
       (async () => {
         setSwitchingFocus(true);
         await livekitRoom?.disconnect();
-        await livekitRoom?.connect(sfuConfig.url, sfuConfig.jwt);
+        await livekitRoom?.connect(sfuConfig!.url, sfuConfig!.jwt);
       })();
     }