### 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
return parse_variable(p_is_static, true);
}
GDScriptParser::VariableNode *GDScriptParser::parse_variable(bool p_is_static, bool p_allow_property) {
	VariableNode *variable = alloc_node<VariableNode>();
	if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected variable name after "var".)")) {
		complete_extents(variable);
		return nullptr;
	}
	variable->identifier = parse_identifier();
	variable->export_info.name = variable->identifier->name;
	variable->is_static = p_is_static;
	if (match(GDScriptTokenizer::Token::COLON)) {
		if (check(GDScriptTokenizer::Token::NEWLINE)) {
			if (p_allow_property) {
				advance();
				return parse_property(variable, true);
			} else {
				push_error(R"(Expected type after ":")");
				complete_extents(variable);
				return nullptr;
			}
		} else if (check((GDScriptTokenizer::Token::EQUAL))) {
			
			variable->infer_datatype = true;
		} else {
			if (p_allow_property) {
				make_completion_context(COMPLETION_PROPERTY_DECLARATION_OR_TYPE, variable);
				if (check(GDScriptTokenizer::Token::IDENTIFIER)) {