### 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
Variant rpc_config;
	GDScriptDataType return_type;
	return_type.has_type = true;
	return_type.kind = GDScriptDataType::BUILTIN;
	return_type.builtin_type = Variant::NIL;
	if (p_func) {
		if (p_func->identifier) {
			func_name = p_func->identifier->name;
		} else {
			func_name = "<anonymous lambda>";
		}
		is_static = p_func->is_static;
		rpc_config = p_func->rpc_config;
		return_type = _gdtype_from_datatype(p_func->get_datatype(), p_script);
	} else {
		if (p_for_ready) {
			func_name = "_ready";
		} else {
			func_name = "@implicit_new";
		}
	}
	codegen.function_name = func_name;
	codegen.is_static = is_static;
	codegen.generator->write_start(p_script, func_name, is_static, rpc_config, return_type);
	int optional_parameters = 0;
	if (p_func) {
		for (int i = 0; i < p_func->parameters.size(); i++) {
			const GDScriptParser::ParameterNode *parameter = p_func->parameters[i];
			GDScriptDataType par_type = _gdtype_from_datatype(parameter->get_datatype(), p_script);
			uint32_t par_addr = codegen.generator->add_parameter(parameter->identifier->name, parameter->initializer != nullptr, par_type);