nhibernateissue.cs

public static class nHibernateExtensions
{
  public static T Transaction<T>(this ISession session, Action<ISession, T> action)
  {
    // 3. Enters here
    using (var tran = session.BeginTransaction()){
      // 4. Calls into the lambda
      return action(tran); 
      // 7. execution continues here
      
    } // 8. Transaction is commited/disposed
    
    // 9. this method returns the task from the action (which is still running)
  }
}

// 1. Execution Starts
public async T DoStuff(){
  // 2. Calls Transaction 
  
  //10. the task is now awaited
 return await _session.Transaction(async session=>
 {
   // 5. Lambda executing
   session.Get<Foo>();
   // 6. We hit the await keyword, this causes this lambda to return
   await SomeAsyncThingo();
   // 11. The async operation returns, now you are playing with a disposed transaction
   session.DoSomethingElse();
 }) 
}