Currently, planar curves (i.e., curves with Vector2 nodes) are treated as space curves. However, planar curves have their own notation of a normal vector, curvature, etc. These should be supported.
Resolved in 38bfac3a09f861520f9b64864dc2bb71349508bd (normal) and fc35e9f36b9f1e1ce0bb74ae04a8fc136f157f63 (curvature). Not sure what I was implying by "etc."
Currently, planar curves (i.e., curves with Vector2 nodes) are treated as space curves. However, planar curves have their own notation of a normal vector, curvature, etc. These should be supported.