If the `wpoly` vector was small, the `wpoly_new` pointer could point to part of its inline buffer on the stack, which becomes invalid out of that scope. Instead, store `wpoly_new` as a span, and assign it properly from the moved vector.
If the `wpoly` vector was small, the `wpoly_new` pointer could point to part of its inline buffer on the stack, which becomes invalid out of that scope. Instead, store `wpoly_new` as a span, and assign it properly from the moved vector.