I just figured a way to bypass this issue: I re-added enough numbers of texture arrays in the texlist profile then the Editor back to normal, though the output node is still ruined.
I just deleted it and recreated one, then I can get back to work 
BTW, @Wright
There is a very promising vegetation system under developing, and the author is trying to integrate with MapMagic.
And now their beta version is free for testers, maybe you can go check them out, make a custom trees and grass output node for their system: Vegetation Studio