BindingExpression.LeafNode throws if nodes list is empty #20441
Description
To Reproduce
A bit exotic one, but:
<TextBlock Text="{Binding Source='Elements', Converter={CasingConverter Upper}}" />
And then use BindingOperations.GetBindingExpressionBase and read BindingExpression.LeafNode or BindingExpression.Description
Expected behavior
BindingExpression.LeafNode is nullable, when nodes list is empty
Avalonia version
11.2.0
OS
No response
Additional context
No response