Add MediaConnectException. (#422)

lib/src/core/engine.dart

@@ -161,12 +161,12 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
 
       logger.fine('Waiting for engine to connect...');
 
-      // wait until engine is connected
+      // wait until primary pc is connected
       await events.waitFor<EnginePeerStateUpdatedEvent>(
         filter: (event) => event.isPrimary && event.state.isConnected(),
         duration: this.connectOptions.timeouts.connection,
-        onTimeout: () => throw ConnectException(
-            'Timed out waiting for EnginePeerStateUpdatedEvent'),
+        onTimeout: () => throw MediaConnectException(
+            'Timed out waiting for PeerConnection to connect, please check your network for ice connectivity'),
       );
 
       _updateConnectionState(ConnectionState.connected);
@@ -646,7 +646,7 @@ class Engine extends Disposable with EventsEmittable<EngineEvent> {
         await events.waitFor<EnginePeerStateUpdatedEvent>(
           filter: (event) => event.isPrimary && event.state.isConnected(),
           duration: connectOptions.timeouts.iceRestart,
-          onTimeout: () => throw ConnectException(),
+          onTimeout: () => throw MediaConnectException('ice restart failed'),
         );
       }
     }

lib/src/exceptions.dart

@@ -30,6 +30,15 @@ class ConnectException extends LiveKitException {
   ConnectException([String msg = 'Failed to connect to server']) : super._(msg);
 }
 
+/// An exception occured while attempting to disconnect.
+/// Common reasons:
+/// - Network condition is not good.
+/// - SFU deploy behind a NAT and not configured correctly.
+/// - Need a turn relay server but not configured.
+class MediaConnectException extends LiveKitException {
+  MediaConnectException([String msg = 'Ice connection failed']) : super._(msg);
+}
+
 /// An internal state of the SDK is not correct and can not continue to execute.
 /// This should not occur frequently.
 class UnexpectedStateException extends LiveKitException {