### 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
if (ResourceLoader::get_resource_type(global_class_path) == "GDScript") {
						Error err = OK;
						res = GDScriptCache::get_full_script(global_class_path, err);
						if (err != OK) {
							_set_error("Can't load global class " + String(identifier), p_expression);
							r_error = ERR_COMPILATION_FAILED;
							return GDScriptCodeGenerator::Address();
						}
					} else {
						res = ResourceLoader::load(global_class_path);
						if (res.is_null()) {
							_set_error("Can't load global class " + String(identifier) + ", cyclic reference?", p_expression);
							r_error = ERR_COMPILATION_FAILED;
							return GDScriptCodeGenerator::Address();
						}
					}
				}
				return codegen.add_constant(res);
			}
#ifdef TOOLS_ENABLED
			if (GDScriptLanguage::get_singleton()->get_named_globals_map().has(identifier)) {
				GDScriptCodeGenerator::Address global = codegen.add_temporary(); 
				gen->write_store_named_global(global, identifier);
				return global;
			}
#endif
			
			_set_error("Identifier not found: " + String(identifier), p_expression);
			r_error = ERR_COMPILATION_FAILED;
			return GDScriptCodeGenerator::Address();