GH-1183 Fix engine freeze when Skeleton3DEditor is deleted on item with many bones

Author: JoltedJon

editor/scene/3d/skeleton_3d_editor_plugin.cpp

@@ -918,6 +918,9 @@ void Skeleton3DEditor::_joint_tree_button_clicked(Object *p_item, int p_column,
 }
 
 void Skeleton3DEditor::_update_properties() {
+	if (is_deleting) {
+		return;
+	}
 	if (pose_editor) {
 		pose_editor->_update_properties();
 	}
@@ -1166,6 +1169,7 @@ void Skeleton3DEditor::_notification(int p_what) {
 			update_joint_tree();
 		} break;
 		case NOTIFICATION_PREDELETE: {
+			is_deleting = true;
 			if (editor_plugin) {
 				editor_plugin->skeleton_editor = nullptr;
 			}

editor/scene/3d/skeleton_3d_editor_plugin.h

@@ -146,6 +146,7 @@ class Skeleton3DEditor : public VBoxContainer {
 	Button *edit_mode_button = nullptr;
 
 	bool edit_mode = false;
+	bool is_deleting = false;
 
 	HBoxContainer *animation_hb = nullptr;
 	Button *key_loc_button = nullptr;