### Godot version

v4.2.beta2.official [f8818f85e]

### System information

Windows 10, 64bit

### Issue description

Some times can't add node in visualshader editor

### Steps to reproduce

1. Open a VisualShader file for edit.
2. Click the `Add Node...` button, it will popup menu, it is OK.
3. Direct close the menu.
4. Clikd the `Add Node...` again, the menu can't popup.
![GIF](https://github.com/godotengine/godot/assets/35988767/1326c63e-3e05-4423-9ec7-7ce305b3f4f5)

### Minimal reproduction project

/
GraphEdit *graph = editor->graph;
	if (!graph) {
		return;
	}
	if (visual_shader.is_valid() && visual_shader->get_shader_type() == p_type) {
		graph->disconnect_node(itos(p_from_node), p_from_port, itos(p_to_node), p_to_port);
		for (const List<VisualShader::Connection>::Element *E = connections.front(); E; E = E->next()) {
			if (E->get().from_node == p_from_node && E->get().from_port == p_from_port && E->get().to_node == p_to_node && E->get().to_port == p_to_port) {
				connections.erase(E);
				break;
			}
		}
		if (links[p_to_node].input_ports.has(p_to_port) && links[p_to_node].input_ports[p_to_port].default_input_button != nullptr && links[p_to_node].visual_node->get_input_port_default_value(p_to_port).get_type() != Variant::NIL) {
			links[p_to_node].input_ports[p_to_port].default_input_button->show();
			set_input_port_default_value(p_type, p_to_node, p_to_port, links[p_to_node].visual_node->get_input_port_default_value(p_to_port));
		}
	}
}
VisualShaderGraphPlugin::~VisualShaderGraphPlugin() {