### 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
codegen.generator->write_assign_with_conversion(dst_address, src_address);
				} else {
					codegen.generator->write_assign(dst_address, src_address);
				}
				if (src_address.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					codegen.generator->pop_temporary();
				}
			}
		}
	}
	
	if (p_func) {
		if (optional_parameters > 0) {
			codegen.generator->start_parameters();
			for (int i = p_func->parameters.size() - optional_parameters; i < p_func->parameters.size(); i++) {
				const GDScriptParser::ParameterNode *parameter = p_func->parameters[i];
				GDScriptCodeGenerator::Address src_addr = _parse_expression(codegen, r_error, parameter->initializer);
				if (r_error) {
					memdelete(codegen.generator);
					return nullptr;
				}
				GDScriptCodeGenerator::Address dst_addr = codegen.parameters[parameter->identifier->name];
				codegen.generator->write_assign_default_parameter(dst_addr, src_addr, parameter->use_conversion_assign);
				if (src_addr.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					codegen.generator->pop_temporary();
				}
			}
			codegen.generator->end_parameters();
		}
		r_error = _parse_block(codegen, p_func->body);