ObjectDB instances leaked at exit

[rubrical-works]

When running your demo and when exiting my own game which has your component, leaked instances are reported. When running the demo, we get this:

ERROR: ~List: Condition "_first != __null" is true.
At: ./core/self_list.h:112
ERROR: ~List: Condition "_first != __null" is true.
At: ./core/self_list.h:112
WARNING: cleanup: ObjectDB instances leaked at exit (run with --verbose for details).
At: core/object.cpp:2135
Leaked instance: GDScript:1508 - Resource path: res://addons/rmsmartshape/vertex_properties.gd
Leaked instance: GDScript:1507 - Resource path: res://addons/rmsmartshape/shapes/point.gd
Leaked instance: GDScript:1451 - Resource path: res://addons/rmsmartshape/normal_range.gd
Leaked instance: GDScript:1557 - Resource path:
Leaked instance: GDScript:1528 - Resource path: res://addons/rmsmartshape/LEGACY_vertex_properties.gd
Leaked instance: GDScript:1511 - Resource path: res://addons/rmsmartshape/shapes/quad.gd
Leaked instance: GDScriptNativeClass:567
Leaked instance: GDScriptNativeClass:571
Hint: Leaked instances typically happen when nodes are removed from the scene tree (with remove_child()) but not freed (with free() or queue_free()).
ERROR: clear: Resources still in use at exit (run with --verbose for details).
At: core/resource.cpp:477
Resource still in use: res://addons/rmsmartshape/vertex_properties.gd (GDScript)
Resource still in use: res://addons/rmsmartshape/shapes/point.gd (GDScript)
Resource still in use: res://addons/rmsmartshape/normal_range.gd (GDScript)
Resource still in use: res://addons/rmsmartshape/LEGACY_vertex_properties.gd (GDScript)
Resource still in use: res://addons/rmsmartshape/shapes/quad.gd (GDScript)
Orphan StringName: res://addons/rmsmartshape/vertex_properties.gd
Orphan StringName: res://addons/rmsmartshape/shapes/quad.gd::102::SS2D_Quad.get_height_average
Orphan StringName: res://addons/rmsmartshape/shapes/quad.gd::26::SS2D