Empty node list is currently not supported

[Adhara3]

The tag BU_: with no nodes produces a parsing error. We should tolerate this.

[Uight]

true and easy enough. and as it is internally a hashset thats always initialized it wouldn't cause the public IEnumerable Nodes {get;} to ever be null which i like ;)

[Adhara3]

@Whitehouse112 can you please take care of this one?

Thx A

[Whitehouse112]

Of course, no problem