Tried importing LightweightPipeline in unity 2018.1.0b12. But I am getting these set of errors. I opened the file using unity hub.
You have first to do the following
-Right Click on your asset - > Create - > Rendering - > any pipeline asset " light or HD"
-on menu, Click Edit → Project setting → Graphics
Now drag and drop the rendering pipeline asset you have created to the setting.
then everything should work fine