### Godot version

v4.0.3.stable.official [5222a99f5]
Master [6101240231600c871f5c5473872532c68ea3268c] (confirmed by https://github.com/godotengine/godot/issues/77666#issuecomment-1568952502)

### System information

Window 10

### Issue description

References are not unreferenced at the end of `if` scopes.

### Steps to reproduce

Copy, paste and run the snippet below, check the results:

```gdscript
extends Node


func _ready() -> void:
  var ref := RefCounted.new()
  var ref_count : int

  # OK
  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)

  # OK
  if true:
    var temp := ref
    temp = null

  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)

  # FAIL
  if true:
    var temp := ref

  ref_count = ref.get_reference_count()
  print('Expected: 1, Result: %d' % ref_count)
```

Output example:

```
Expected: 1, Result: 1
Expected: 1, Result: 1
Expected: 1, Result: 2
```

### Minimal reproduction project

N/A
}
				break;
			case GDScriptParser::DataType::CLASS:
				if (ClassDB::is_parent_class(export_type.native_type, SNAME("Resource"))) {
					variable->export_info.type = Variant::OBJECT;
					variable->export_info.hint = PROPERTY_HINT_RESOURCE_TYPE;
					variable->export_info.hint_string = export_type.to_string();
				} else if (ClassDB::is_parent_class(export_type.native_type, SNAME("Node"))) {
					variable->export_info.type = Variant::OBJECT;
					variable->export_info.hint = PROPERTY_HINT_NODE_TYPE;
					variable->export_info.hint_string = export_type.to_string();
				} else {
					push_error(R"(Export type can only be built-in, a resource, a node, or an enum.)", variable);
					return false;
				}
				break;
			case GDScriptParser::DataType::SCRIPT: {
				StringName class_name;
				StringName native_base;
				if (export_type.script_type.is_valid()) {
					class_name = export_type.script_type->get_language()->get_global_class_name(export_type.script_type->get_path());
					native_base = export_type.script_type->get_instance_base_type();
				}
				if (class_name == StringName()) {
					Ref<Script> script = ResourceLoader::load(export_type.script_path, SNAME("Script"));
					if (script.is_valid()) {
						class_name = script->get_language()->get_global_class_name(export_type.script_path);
						native_base = script->get_instance_base_type();
					}
				}