### Godot version

4.1

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description


https://github.com/godotengine/godot/assets/2223172/3c8ee782-9d5f-42e3-a70f-d2aa59a233dd

We correctly clamp the size to 16x16 everywhere except here (probably).

### Steps to reproduce

1. Add a class with custom icon, e.g.
```GDScript
@icon("res://icon.svg")
extends Node
class_name Icon
```
2. Add it to scene
3. Open Script Editor and drag the node to script editor

### Minimal reproduction project

N/A
ERR_FAIL_COND(blocked > 0);
	if (pending_test_update) {
		_test_update_tree();
	}
	if (tree_dirty) {
		_update_tree();
	}
	if (selected == p_node) {
		return;
	}
	TreeItem *item = p_node ? _find(tree->get_root(), p_node->get_path()) : nullptr;
	if (item) {
		if (auto_expand_selected) {
			// M
			TreeItem *node = item->get_parent();