I don't know if this would be a bug or not, but if you have a node with a space in the name, it lets you use it, despite that it crashes if you try to load a save with that node. It seems like either it shouldn't crash or it shouldn't let you use the node. (like how it doesn't show in the list or shows the default node if the node has a bug in it)
It also seems like the Lighting node changes contrast based on tile size.