Added a workaround to avoid crashes due to how TileSet editor works, fixes #23672

Also fixed a few uninitialized memory variables.

editor/editor_node.cpp

@@ -1370,6 +1370,9 @@ bool EditorNode::item_has_editor(Object *p_object) {
 	return editor_data.get_subeditors(p_object).size() > 0;
 }
 
+void EditorNode::edit_item_resource(RES p_resource) {
+	edit_item(p_resource.ptr());
+}
 void EditorNode::edit_item(Object *p_object) {
 
 	Vector<EditorPlugin *> sub_plugins;
@@ -4730,6 +4733,7 @@ void EditorNode::_bind_methods() {
 	ClassDB::bind_method("_clear_undo_history", &EditorNode::_clear_undo_history);
 	ClassDB::bind_method("_dropped_files", &EditorNode::_dropped_files);
 	ClassDB::bind_method("_toggle_distraction_free_mode", &EditorNode::_toggle_distraction_free_mode);
+	ClassDB::bind_method("edit_item_resource", &EditorNode::edit_item_resource);
 
 	ClassDB::bind_method(D_METHOD("get_gui_base"), &EditorNode::get_gui_base);
 	ClassDB::bind_method(D_METHOD("_bottom_panel_switch"), &EditorNode::_bottom_panel_switch);

editor/editor_node.h

@@ -673,6 +673,7 @@ public:
 
 	void push_item(Object *p_object, const String &p_property = "", bool p_inspector_only = false);
 	void edit_item(Object *p_object);
+	void edit_item_resource(RES p_resource);
 	bool item_has_editor(Object *p_object);
 
 	void open_request(const String &p_path);

editor/editor_properties.cpp

@@ -2439,7 +2439,7 @@ void EditorPropertyResource::_button_input(const Ref<InputEvent> &p_event) {
 void EditorPropertyResource::_open_editor_pressed() {
 	RES res = get_edited_object()->get(get_edited_property());
 	if (res.is_valid()) {
-		EditorNode::get_singleton()->edit_item(res.ptr());
+		EditorNode::get_singleton()->call_deferred("edit_item_resource", res); //may clear the editor so do it deferred
 	}
 }
 

editor/plugins/item_list_editor_plugin.cpp

@@ -353,6 +353,7 @@ void ItemListEditor::_bind_methods() {
 ItemListEditor::ItemListEditor() {
 
 	selected_idx = -1;
+	item_list = NULL;
 
 	toolbar_button = memnew(ToolButton);
 	toolbar_button->set_text(TTR("Items"));

editor/plugins/tile_set_editor_plugin.cpp

@@ -2705,6 +2705,7 @@ void TilesetEditorContext::_bind_methods() {
 TilesetEditorContext::TilesetEditorContext(TileSetEditor *p_tileset_editor) {
 
 	tileset_editor = p_tileset_editor;
+	snap_options_visible = false;
 }
 
 void TileSetEditorPlugin::edit(Object *p_node) {

scene/main/viewport.cpp

@@ -3202,6 +3202,8 @@ Viewport::Viewport() {
 	gui.drag_attempted = false;
 	gui.canvas_sort_index = 0;
 	gui.roots_order_dirty = false;
+	gui.mouse_focus = NULL;
+	gui.last_mouse_focus = NULL;
 
 	msaa = MSAA_DISABLED;
 	hdr = true;