### 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
assignment->assignee = p_previous_operand;
	assignment->assigned_value = parse_expression(false);
	if (assignment->assigned_value == nullptr) {
		push_error(R"(Expected an expression after "=".)");
	}
	complete_extents(assignment);
#ifdef DEBUG_ENABLED
	if (source_variable != nullptr) {
		if (has_operator && source_variable->assignments == 0) {
			push_warning(assignment, GDScriptWarning::UNASSIGNED_VARIABLE_OP_ASSIGN, source_variable->identifier->name);
		}
		source_variable->assignments += 1;
	}
#endif
	return assignment;
}
GDScriptParser::ExpressionNode *GDScriptParser::parse_await(ExpressionNode *p_previous_operand, bool p_can_assign) {
	AwaitNode *await = alloc_node<AwaitNode>();
	ExpressionNode *element = parse_precedence(PREC_AWAIT, false);
	if (element == nullptr) {
		push_error(R"(Expected signal or coroutine after "await".)");
	}
	await->to_await = element;
	complete_extents(await);
	if (current_function) { 
		current_function->is_coroutine = true;
	}
	return await;
}
GDScriptParser::ExpressionNode *GDScriptParser::parse_array(ExpressionNode *p_previous_operand, bool p_can_assign) {