### 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
token_type = GDScriptTokenizer::Token::IDENTIFIER;
	}
	ParseFunction prefix_rule = get_rule(token_type)->prefix;
	if (prefix_rule == nullptr) {
		
		return nullptr;
	}
	advance(); 
	ExpressionNode *previous_operand = (this->*prefix_rule)(nullptr, p_can_assign);
	while (p_precedence <= get_rule(current.type)->precedence) {
		if (previous_operand == nullptr || (p_stop_on_assign && current.type == GDScriptTokenizer::Token::EQUAL) || lambda_ended) {
			return previous_operand;
		}
		
		switch (current.type) {
			
			case GDScriptTokenizer::Token::PARENTHESIS_OPEN:
			case GDScriptTokenizer::Token::BRACKET_OPEN:
				push_multiline(true);
				break;
			default:
				break; 
		}
		token = advance();
		ParseFunction infix_rule = get_rule(token.type)->infix;
		previous_operand = (this->*infix_rule)(previous_operand, p_can_assign);
	}
	return previous_operand;
}
GDScriptParser::ExpressionNode *GDScriptParser::parse_expression(bool p_can_assign, bool p_stop_on_assign) {