When you need to take a picture of a graph, you can zoom in until the nodes are readable, then click the camera icon in the top right to take a full picture of the graph. It makes it easier to understand.
The errors are coming from the curves/inputs. “PolyCurves may not be branching” means that the curves do not form a single continuous line. Could be a problem with directions of the curves or the points not lining up. Can’t say without seeing the curves themselves.
“Dereferencing a non-pointer” means the input includes something that cannot be used by the node, usually a ‘null’, which you can see is in the watch list at positions 0, 8, 9, etc. These nulls are because the polycurve node failed in the lists at indices 0, 8, 9, etc.
Go back and check the list of curves at any indices where there is a null. There is a problem with those curves.