### 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::NATIVE: {
			result.kind = GDScriptDataType::NATIVE;
			result.native_type = p_datatype.native_type;
			result.builtin_type = p_datatype.builtin_type;
		} break;
		case GDScriptParser::DataType::SCRIPT: {
			result.kind = GDScriptDataType::SCRIPT;
			result.builtin_type = p_datatype.builtin_type;
			result.script_type_ref = p_datatype.script_type;
			result.script_type = result.script_type_ref.ptr();
			result.native_type = p_datatype.native_type;
		} break;
		case GDScriptParser::DataType::CLASS: {
			result.kind = GDScriptDataType::GDSCRIPT;
			result.builtin_type = p_datatype.builtin_type;
			result.native_type = p_datatype.native_type;
			bool is_local_class = parser->has_class(p_datatype.class_type);
			Ref<GDScript> script;
			if (is_local_class) {
				script = Ref<GDScript>(main_script);
			} else {
				Error err = OK;
				script = GDScriptCache::get_shallow_script(p_datatype.script_path, err, p_owner->path);
				if (err) {
					_set_error(vformat(R"(Could not find script "%s": %s)", p_datatype.script_path, error_names[err]), nullptr);
				}
			}
			if (script.is_valid()) {
				script = Ref<GDScript>(script->find_class(p_datatype.class_type->fqcn));