### 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
#include "gdscript_parser.h"
#include "gdscript.h"
#ifdef DEBUG_ENABLED
#include "gdscript_warning.h"
#endif
#include "core/config/project_settings.h"
#include "core/io/file_access.h"
#include "core/io/resource_loader.h"
#include "core/math/math_defs.h"
#include "scene/main/multiplayer_api.h"
#ifdef DEBUG_ENABLED
#include "core/os/os.h"
#include "core/string/string_builder.h"
#include "servers/text_server.h"
#endif
#ifdef TOOLS_ENABLED
#include "editor/editor_settings.h"
#endif
static HashMap<StringName, Variant::Type> builtin_types;
Variant::Type GDScriptParser::get_builtin_type(const StringName &p_type) {