Fix typecheck errors and improve WebSocket transport implementation

- Fix INotifee interface compliance in WebSocket demo
- Fix handler function signatures to be async (THandler compatibility)
- Fix is_closed method usage with proper type checking
- Fix pytest.raises multiple exception type issue
- Fix line length violations (E501) across multiple files
- Add debugging logging to Noise security module for troubleshooting
- Update WebSocket transport examples and tests
- Improve transport registry error handling

libp2p/transport/__init__.py

@@ -1,17 +1,19 @@
 from .tcp.tcp import TCP
 from .websocket.transport import WebsocketTransport
 from .transport_registry import (
-    TransportRegistry, 
+    TransportRegistry,
     create_transport_for_multiaddr,
     get_transport_registry,
     register_transport,
     get_supported_transport_protocols,
 )
+from .upgrader import TransportUpgrader
+from libp2p.abc import ITransport
 
-def create_transport(protocol: str, upgrader=None):
+def create_transport(protocol: str, upgrader: TransportUpgrader | None = None) -> ITransport:
     """
     Convenience function to create a transport instance.
-    
+
     :param protocol: The transport protocol ("tcp", "ws", or custom)
     :param upgrader: Optional transport upgrader (required for WebSocket)
     :return: Transport instance
@@ -28,7 +30,10 @@ def create_transport(protocol: str, upgrader=None):
         registry = get_transport_registry()
         transport_class = registry.get_transport(protocol)
         if transport_class:
-            return registry.create_transport(protocol, upgrader)
+            transport = registry.create_transport(protocol, upgrader)
+            if transport is None:
+                raise ValueError(f"Failed to create transport for protocol: {protocol}")
+            return transport
         else:
             raise ValueError(f"Unsupported transport protocol: {protocol}")