Crash when reordering objects with shadows

Summary:

Crash when reordering objects with shadows

Steps to reproduce:

  • open Inkscape
  • draw a circle with border and no fill
  • Add in-out shadow to it
  • Add another object
  • Try to reorder them
  • See a crash

Sample attachments:

<pre>
 0# Inkscape::Application::crash_handler(int) in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
 1# 0x00007470DF85A770 in /usr/lib/libc.so.6
 2# 0x00007470DF8AB32C in /usr/lib/libc.so.6
 3# gsignal in /usr/lib/libc.so.6
 4# abort in /usr/lib/libc.so.6
 5# 0x00007470DFADD3B2 in /usr/lib/libstdc++.so.6
 6# BlurKnotHolderEntity::_pos() const in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
 7# BlurKnotHolderEntity::knot_get() const in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
 8# KnotHolderEntity::update_knot() in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
 9# KnotHolderEntity::create(SPDesktop*, SPItem*, KnotHolder*, Inkscape::CanvasItemCtrlType, Glib::ustring const&, char const*, unsigned int) in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
10# KnotHolder::add_filter_knotholder() in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
11# Inkscape::UI::createKnotHolder(SPItem*, SPDesktop*, double, int) in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
12# Inkscape::UI::ShapeEditor::set_item(SPItem*) in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
13# Inkscape::Selection::_emitChanged(bool) in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
14# Inkscape::ObjectSet::toLayer(SPObject*, Inkscape::XML::Node*) in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
15# Inkscape::UI::Dialog::ObjectsPanel::on_drag_drop(Glib::RefPtr<Gdk::DragContext> const&, int, int, unsigned int) in /usr/bin/../lib/inkscape/libinkscape_base.so.1.3.2.0
16# 0x00007470DE508BB1 in /usr/bin/../lib/inkscape/../libgtkmm-3.0.so.1
17# 0x00007470DD886675 in /usr/bin/../lib/inkscape/../libgtk-3.so.0
18# g_closure_invoke in /usr/bin/../lib/inkscape/../libgobject-2.0.so.0
19# 0x00007470DF38EA36 in /usr/bin/../lib/inkscape/../libgobject-2.0.so.0
20# 0x00007470DF37F335 in /usr/bin/../lib/inkscape/../libgobject-2.0.so.0
21# g_signal_emit_by_name in /usr/bin/../lib/inkscape/../libgobject-2.0.so.0
22# 0x00007470DDB836C5 in /usr/bin/../lib/inkscape/../libgtk-3.so.0
23# gtk_main_do_event in /usr/bin/../lib/inkscape/../libgtk-3.so.0
24# 0x00007470DE0B9B77 in /usr/bin/../lib/inkscape/../libgdk-3.so.0
25# 0x00007470DE112438 in /usr/bin/../lib/inkscape/../libgdk-3.so.0
26# 0x00007470DFF0DF69 in /usr/lib/libglib-2.0.so.0
27# 0x00007470DFF6C3A7 in /usr/lib/libglib-2.0.so.0
28# g_main_context_iteration in /usr/lib/libglib-2.0.so.0
29# g_application_run in /usr/bin/../lib/inkscape/../libgio-2.0.so.0
30# main in inkscape
31# 0x00007470DF843CD0 in /usr/lib/libc.so.6
32# __libc_start_main in /usr/lib/libc.so.6
33# _start in inkscape
</pre>
<details><summary>System info</summary>
Inkscape 1.3.2 (091e20ef0f, 2023-11-25, custom)

    GLib version:     2.78.4
    GTK version:      3.24.41
    glibmm version:   2.66.6
    gtkmm version:    3.24.8
    libxml2 version:  2.12.3
    libxslt version:  1.1.39
    Cairo version:    1.18.0
    Pango version:    1.51.0
    HarfBuzz version: 8.3.0

    OS version:       Arch Linux
</details>

2024-02-16_02-25-06