DegeneratePolylineException
The rejection of a vertex list that chains into no polyline.
Thrown by the Polyline constructor for fewer than 2 vertices, a vertex at infinity, or two consecutive vertices coinciding at the SCALE quantum — their shared edge would collapse, the same coincident-endpoint rule Segment enforces. Unlike Polygon there is no last→first wrap check: a chain may revisit points, the first and last included.