The class EndpointReachedEvent (in NestedMarkupExtension.cs) has a static field "listeners" and a bunch of static methods. The methods assume that the field was initialized. However, since there is no static constructor, the class is marked as
beforefieldinit, which means that it is possible for the methods to be run before the field is initialized (i.e. it is null). This results in a crash. See
The fix would be to add an empty static constructor to the class.