Mermaid treats ';' as a statement separator, so the label
'lastPos (== start; re-sync)' terminated mid-line and the parser then
expected an arrow (the 'Parse error on line 59' the preview showed).
Removed the semicolon and, defensively, replaced 'Iterable<Point>' with
plain text so the angle brackets aren't interpreted as an HTML tag in the
rendered label.
nokeo08