### 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
type = GET_NODE;
		}
	};
	struct IdentifierNode : public ExpressionNode {
		StringName name;
		enum Source {
			UNDEFINED_SOURCE,
			FUNCTION_PARAMETER,
			LOCAL_CONSTANT,
			LOCAL_VARIABLE,
			LOCAL_ITERATOR, 
			LOCAL_BIND, 
			MEMBER_SIGNAL,
			MEMBER_VARIABLE,
			STATIC_VARIABLE,
			MEMBER_CONSTANT,
			INHERITED_VARIABLE,
		};
		Source source = UNDEFINED_SOURCE;
		union {
			ParameterNode *parameter_source = nullptr;
			ConstantNode *constant_source;
			VariableNode *variable_source;
			IdentifierNode *bind_source;
		};
		FunctionNode *source_function = nullptr;
		int usages = 0; 
		IdentifierNode() {