### 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
GDScriptDataType type;
			type.has_type = true;
			type.kind = GDScriptDataType::BUILTIN;
			type.builtin_type = p_constant.get_type();
			if (type.builtin_type == Variant::OBJECT) {
				Object *obj = p_constant;
				if (obj) {
					type.kind = GDScriptDataType::NATIVE;
					type.native_type = obj->get_class_name();
					Ref<Script> scr = obj->get_script();
					if (scr.is_valid()) {
						type.script_type = scr.ptr();
						Ref<GDScript> gdscript = scr;
						if (gdscript.is_valid()) {
							type.kind = GDScriptDataType::GDSCRIPT;
						} else {
							type.kind = GDScriptDataType::SCRIPT;
						}
					}
				} else {
					type.builtin_type = Variant::NIL;
				}
			}
			uint32_t addr = generator->add_or_get_constant(p_constant);
			return GDScriptCodeGenerator::Address(GDScriptCodeGenerator::Address::CONSTANT, addr, type);
		}
		void start_block() {