Inkscape moves pencil shape to random location if line ends at line start
#### Summary:
See attached video. Drawing with the pen teleports the line outside the page if you start and end in the same place.
#### Steps to reproduce:
Draw line from beginning to end
#### What happened?
Teleportation
#### What should have happened?
No teleportation.
Sample attachments:
{width=900 height=507}
#### Version info
```
Inkscape 1.4.3 (0d15f75042, 2025-12-25)
Compile (Run)
GLib version: 2.86.3
GTK version: 3.24.51 (3.24.52)
glibmm version: 2.66.1
gtkmm version: 3.24.5
libxml2 version: 2.14.6
libxslt version: 1.1.43
Cairo version: 1.18.4 (1.18.4)
Pango version: 1.57.0 (1.57.1)
HarfBuzz version: 11.4.5 (11.4.5)
OS version: GNOME 49 (Flatpak runtime)
```
Also had a crash an hour ago while drawing, don't know if it might be related:
```sh
<pre>
0# Inkscape::Application::crash_handler(int) in /app/bin/../lib/inkscape/libinkscape_base.so.1.4.3.0
1# 0x00007514060434F0 in /usr/lib/x86_64-linux-gnu/libc.so.6
2# 0x000075140609D51C in /usr/lib/x86_64-linux-gnu/libc.so.6
3# gsignal in /usr/lib/x86_64-linux-gnu/libc.so.6
4# abort in /usr/lib/x86_64-linux-gnu/libc.so.6
5# 0x00007514062B55CA in /usr/lib/x86_64-linux-gnu/libstdc++.so.6
6# 0x00007514074026CC in /app/bin/../lib/inkscape/libinkscape_base.so.1.4.3.0
7# Inkscape::UI::Tools::PencilTool::_handleButtonRelease(Inkscape::ButtonReleaseEvent const&) in /app/bin/../lib/inkscape/libinkscape_base.so.1.4.3.0
8# Inkscape::UI::Tools::PencilTool::root_handler(Inkscape::CanvasEvent const&) in /app/bin/../lib/inkscape/libinkscape_base.so.1.4.3.0
9# Inkscape::UI::Widget::CanvasPrivate::emit_event(Inkscape::CanvasEvent&) in /app/bin/../lib/inkscape/libinkscape_base.so.1.4.3.0
10# Inkscape::UI::Widget::CanvasPrivate::process_event(Inkscape::CanvasEvent&) in /app/bin/../lib/inkscape/libinkscape_base.so.1.4.3.0
11# Inkscape::UI::Widget::Canvas::on_button_release_event(_GdkEventButton*) in /app/bin/../lib/inkscape/libinkscape_base.so.1.4.3.0
12# Gtk::Widget_Class::button_release_event_callback(_GtkWidget*, _GdkEventButton*) in /app/bin/../lib/inkscape/../libgtkmm-3.0.so.1
13# 0x00007514042AE191 in /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
14# 0x000075140653F8A6 in /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
15# 0x000075140655654D in /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
16# g_signal_emit_valist in /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
17# g_signal_emit in /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
18# 0x000075140458816D in /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
19# 0x00007514044284B8 in /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
20# gtk_main_do_event in /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
21# 0x0000751404131911 in /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
22# 0x0000751404190BEE in /usr/lib/x86_64-linux-gnu/libgdk-3.so.0
23# 0x000075140690390B in /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
24# 0x0000751406906D47 in /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
25# g_main_context_iteration in /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
26# g_application_run in /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0
27# main in inkscape
28# 0x000075140602C975 in /usr/lib/x86_64-linux-gnu/libc.so.6
29# __libc_start_main in /usr/lib/x86_64-linux-gnu/libc.so.6
30# _start in inkscape
`</pre>`
<details><summary>System info</summary>
Inkscape 1.4.3 (0d15f75042, 2025-12-25)
Compile (Run)
GLib version: 2.86.3
GTK version: 3.24.51 (3.24.52)
glibmm version: 2.66.1
gtkmm version: 3.24.5
libxml2 version: 2.14.6
libxslt version: 1.1.43
Cairo version: 1.18.4 (1.18.4)
Pango version: 1.57.0 (1.57.1)
HarfBuzz version: 11.4.5 (11.4.5)
OS version: GNOME 49 (Flatpak runtime)
</details>
```
issue