1. Solution exception:Object reference not set to an instance of an object

Hello guys,
I am a newbie at Rhino, and I know nothing about Grasshopper and C#.
Because the requirements in my work, I need to use Rhino as the main program for my nesting, and this tedious job usually take me 2-3 away from my main work. I found Opennest, and really grateful for it, but i run into a problem as shown in the pictures, and I cannot work my way through it.
In the Rhino files, all the curve is closed. I can nest the purple bits, but when i add the brown it shows the error in the title. If it is possible, could you guys have a look of my files, I would be very grateful.
Sorry for my potato english.
I have attached the files
Testing.3dm (2.4 MB)
opennest.gh (11.9 KB)