Hi tj62;
There are several options that I know of to minimize the error of binding with a property that doesn't exist:
1. When debugging, the debug output window should show something like this in the event of binding error.
System.Windows.Data Error: BindingExpression path error: 'Outputxxxxx' property not found on 'SilverlightApplication1.MainPageViewModel' 'SilverlightApplication1.MainPageViewModel' (HashCode=53180767). BindingExpression: Path='Outputxxxxx' DataItem='SilverlightApplication1.MainPageViewModel' (HashCode=53180767); target element is 'System.Windows.Controls.TextBox' (Name='txtOutput'); target property is 'Text' (type 'System.String')..
2. You can use a Fallback value markup as a default value in case a binding error occurs.
<TextBox Name="txtOutput"
Text="{Binding Outputxxxxx, FallbackValue='Binding has failed'}"
3. By googling this, I was able to find other options that other developers seem to use. One of them that I think is more helpful than the rest is this.
Hope this helps.