Fix #135517: Geometry nodes convex hull imprecision

The equivalent operation in edit mode reused existing vertices
rather than taking the new positions from the convex hull output.
This commit implements the same behavior for the geometry node.

Pull Request: https://projects.blender.org/blender/blender/pulls/135536

source/blender/nodes/geometry/nodes/node_geo_convex_hull.cc

@@ -52,20 +52,15 @@ static Mesh *hull_from_bullet(const Mesh *mesh, Span<float3> coords)
   /* Copy vertices. */
   MutableSpan<float3> dst_positions = result->vert_positions_for_write();
   for (const int i : IndexRange(verts_num)) {
+    float3 dummy_co;
     int original_index;
-    plConvexHullGetVertex(hull, i, dst_positions[i], &original_index);
-
-    if (original_index >= 0 && original_index < coords.size()) {
-#  if 0 /* Disabled because it only works for meshes, not predictable enough. */
-      /* Copy custom data on vertices, like vertex groups etc. */
-      if (mesh && original_index < mesh->verts_num) {
-        CustomData_copy_data(&mesh->vert_data, &result->vert_data, int(original_index), int(i), 1);
-      }
-#  endif
-    }
-    else {
-      BLI_assert_msg(0, "Unexpected new vertex in hull output");
+    plConvexHullGetVertex(hull, i, dummy_co, &original_index);
+    if (UNLIKELY(!coords.index_range().contains(original_index))) {
+      BLI_assert_unreachable();
+      dst_positions[i] = float3(0);
+      continue;
     }
+    dst_positions[i] = coords[original_index];
   }
 
   /* Copy edges and loops. */