The polyline arm of the hatch wire outline guarded its NaN separator
with `if count > 0 && pts.len() != start_idx`. `start_idx` was assigned
to `pts.len()` two lines earlier with nothing in between to grow `pts`,
so the inequality was structurally always false — the separator was
never emitted.
When a hatch carried more than one boundary path (multi-region hatch),
the renderer drew a straight segment from the last vertex of path A to
the first vertex of path B because the two polylines lived in `pts`
back-to-back with no NaN break. The result was a visible stray line
between hatch regions.
Switch the polyline arm to the same `if !pts.is_empty()` guard the
Line / CircularArc / EllipticArc arms use, and capture `start_idx`
*after* the separator so the closed-loop close-back logic still points
at this polyline's first real vertex.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
a3e9b05130