fix Dialogs is null

[hchen2020]

No description provided.

[GGHansome]

Auto Review Result:

Problem Category	Problem Description	Suggested Improvement
Null Checks	The code lacks null checks for Dialogs before using it with LINQ operations.	Ensure Dialogs is not null before proceeding with operations.
Code Readability	Adding null check handling directly at the beginning might be sudden without comment.	Add comments explaining why this null check is critical.
Method Utilization	Null checking at the start of the method might indicate a deeper issue with the data flow.	Consider ensuring that Dialogs is initialized properly to manage null checks efficiently.

Code Example Update

Current Code:

public override async Task OnMessageReceived(RoleDialogModel message)
{
    if (Dialogs == null)
    {
        return;
    }

    // Check message sending frequency
    var userSents = Dialogs.Where(x => x.Role == AgentRole.User)
        .TakeLast(2).ToList();
}

Suggested Improvement:

public override async Task OnMessageReceived(RoleDialogModel message)
{
    // Ensure Dialogs is initialized
    if (Dialogs == null)
    {
        // It's critical to verify if Dialogs is null to prevent runtime exceptions
        return;
    }

    // Check message sending frequency
    var userSents = Dialogs.Where(x => x.Role == AgentRole.User)
        .TakeLast(2).ToList();
}

• Additionally, if Dialogs being null is a common scenario, you might consider initializing it in the constructor or method responsible for setting it.