Exceptions thrown on message enqueue

[ASutrick]

On my MainWindowViewModel I have the following functions defined:

public void ShowSuccessMessage(string message)
{
    Manager.CreateMessage()
       .Foreground("#000000")
       .Background("#5BF58B")
       .HasMessage(message)
       .Dismiss().WithDelay(TimeSpan.FromSeconds(5))
       .Queue();
}
public void ShowErrorMessage(string message)
{ 
    Manager.CreateMessage()
        .Foreground("#000000")
        .Background("#F55B5B")
        .HasMessage(message)
        .Dismiss().WithDelay(TimeSpan.FromSeconds(5))
        .Queue();
}

The notifications pop up and dismiss as expected. When I check debug output, I see that every time a notification is queued the following exceptions are thrown multiple times:
"[Binding]Error in binding to 'Avalonia.Controls.TextBlock'.'Background': 'Null value in expression '{empty}' at ''.'(TextBlock)",
"[Binding]Error in binding to 'Avalonia.Controls.TextBlock'.'Foreground': 'Null value in expression '{empty}' at ''.'(TextBlock )"

It doesn't cause a crash and the back/foreground color is correct. I was wondering if anyone else is getting these, or if its an issue with how I set it up?