### 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
if (!for_completion) {
		return;
	}
	CompletionCall call;
	call.call = p_call;
	call.argument = 0;
	completion_call_stack.push_back(call);
	if (previous.cursor_place == GDScriptTokenizer::CURSOR_MIDDLE || previous.cursor_place == GDScriptTokenizer::CURSOR_END || current.cursor_place == GDScriptTokenizer::CURSOR_BEGINNING) {
		completion_call = call;
	}
}
void GDScriptParser::pop_completion_call() {
	if (!for_completion) {
		return;
	}
	ERR_FAIL_COND_MSG(completion_call_stack.is_empty(), "Trying to pop empty completion call stack");
	completion_call_stack.pop_back();
}
void GDScriptParser::set_last_completion_call_arg(int p_argument) {
	if (!for_completion || passed_cursor) {
		return;
	}
	ERR_FAIL_COND_MSG(completion_call_stack.is_empty(), "Trying to set argument on empty completion call stack");
	completion_call_stack.back()->get().argument = p_argument;
}
Error GDScriptParser::parse(const String &p_source_code, const String &p_script_path, bool p_for_completion) {