add comment for getActiveSession

Author: jiexi

packages/connect-multichain/src/multichain/transports/default/index.ts

@@ -312,6 +312,9 @@ export class DefaultTransport implements ExtendedTransport {
   }
 
   getActiveSession(): Promise<Session | undefined> {
+    // This code path should never be triggered when the DefaultTransport is being used
+    // It's only purpose is for exposing the session ID used for deeplinking to the mobile app
+    // and so it is only implemented for the MWPTransport.
     throw new Error('getActiveSession is purposely not implemented for the DefaultTransport');
   }
 }