### Godot version

ef025711a

### System information

ArchLinux x11

### Issue description

Accessing a scene unique node like this:
```gdscript
class_name Class extends Node
static func get_label() -> Label:
	return %label
```
and then accessing that class later:
```gdscript
func _ready() -> void:
	Main.get_label().text = "hello world"
```
causes a strange error when in the editor, and a normal error when run directly.
![image](https://user-images.githubusercontent.com/70787919/229785642-6aad4e31-6bd9-4eb5-bee4-7445b48a99bb.png)
```c++
ERROR: Node not found: "%label" (relative to "/root/main").
   at: get_node (scene/main/node.cpp:1364)
```
Instead of returning null.
As opposed to when using `get_node`:
```

SCRIPT ERROR: Cannot call method 'get_node' on a null value.
          at: get_label (res://main.gd:5)
SCRIPT ERROR: Invalid set index 'text' (on base: 'Nil') with value of type 'String'.
          at: _ready (res://control.gd:4)
```

### Steps to reproduce

Run mrp or follow outlined steps

### Minimal reproduction project

[bug.zip](https://github.com/godotengine/godot/files/11148287/bug.zip)

if (p_assignment->operation == GDScriptParser::AssignmentNode::OP_NONE && assignee_type.is_hard_type() && p_assignment->assigned_value->is_constant) {
		update_const_expression_builtin_type(p_assignment->assigned_value, assignee_type, "assign");
	}
	GDScriptParser::DataType assigned_value_type = p_assignment->assigned_value->get_datatype();
	bool assignee_is_variant = assignee_type.is_variant();
	bool assignee_is_hard = assignee_type.is_hard_type();
	bool assigned_is_variant = assigned_value_type.is_variant();
	bool assigned_is_hard = assigned_value_type.is_hard_type();
	bool compatible = true;
	bool downgrades_assignee = false;
	bool downgrades_assigned = false;
	GDScriptParser::DataType op_type = assigned_value_type;
	if (p_assignment->operation != GDScriptParser::AssignmentNode::OP_NONE && !op_type.is_variant()) {
		op_type = get_operation_type(p_assignment->variant_op, assignee_type, assigned_value_type, compatible, p_assignment->assigned_value);
		if (assignee_is_variant) {
			
			mark_node_unsafe(p_assignment);
		} else if (!compatible) {
			
			mark_node_unsafe(p_assignment);
			if (assigned_is_variant) {
				
				p_assignment->use_conversion_assign = true;
			} else {
				
				push_error(vformat(R"(Invalid operands "%s" and "%s" for assignment operator.)", assignee_type.to_string(), assigned_value_type.to_string()), p_assignment);
			}
		} else if (op_type.type_source == GDScriptParser::DataType::UNDETECTED && !assigned_is_variant) {
			
			downgrades_assignee = !assignee_is_hard;