### 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 (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected parameter name.)")) {
		return nullptr;
	}
	ParameterNode *parameter = alloc_node<ParameterNode>();
	parameter->identifier = parse_identifier();
	if (match(GDScriptTokenizer::Token::COLON)) {
		if (check((GDScriptTokenizer::Token::EQUAL))) {
			
			parameter->infer_datatype = true;
		} else {
			
			make_completion_context(COMPLETION_TYPE_NAME, parameter);
			parameter->datatype_specifier = parse_type();
		}
	}
	if (match(GDScriptTokenizer::Token::EQUAL)) {
		
		parameter->initializer = parse_expression(false);
	}
	complete_extents(parameter);
	return parameter;
}
GDScriptParser::SignalNode *GDScriptParser::parse_signal(bool p_is_static) {
	SignalNode *signal = alloc_node<SignalNode>();
	if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected signal name after "signal".)")) {
		complete_extents(signal);
		return nullptr;
	}
	signal->identifier = parse_identifier();
	if (check(GDScriptTokenizer::Token::PARENTHESIS_OPEN)) {