PicoVector: Fix bug in polygon iterator.

list(Polygon) should return a list of points, but crashed with non-empty polygons.

We were advancing to the next path and then retriving an invalid point count for building the tuple.

Save the point count before advancing to the next path.

micropython/modules/picovector/picovector.cpp

@@ -507,12 +507,12 @@ static mp_obj_t POLYGON_it_iternext(mp_obj_t self_in) {
     mp_obj_polygon_it_t *self = MP_OBJ_TO_PTR2(self_in, mp_obj_polygon_it_t);
     //_POLY_obj_t *poly = MP_OBJ_TO_PTR2(self->polygon, _POLY_obj_t);
 
-    //mp_printf(&mp_plat_print, "points: %d, current: %d\n", polygon->contour.count, self->cur);
-
     if(!self->cur) return MP_OBJ_STOP_ITERATION;
 
-    mp_obj_t tuple[self->cur->count];
-    for (auto i = 0; i < self->cur->count; i++) {
+    int count = self->cur->count;
+
+    mp_obj_t tuple[count];
+    for (auto i = 0; i < count; i++) {
         mp_obj_t t_point[2] = {
             mp_picovector_set_point_type((int)(self->cur->points[i].x)),
             mp_picovector_set_point_type((int)(self->cur->points[i].y))
@@ -521,7 +521,7 @@ static mp_obj_t POLYGON_it_iternext(mp_obj_t self_in) {
     }
 
     self->cur = self->cur->next;
-    return mp_obj_new_tuple(self->cur->count, tuple);
+    return mp_obj_new_tuple(count, tuple);
 }
 
 mp_obj_t POLYGON_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf) {