### 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
GDScriptCodeGenerator::Address call_base = is_static ? GDScriptCodeGenerator::Address(GDScriptCodeGenerator::Address::CLASS) : GDScriptCodeGenerator::Address(GDScriptCodeGenerator::Address::SELF);
					gen->write_call(GDScriptCodeGenerator::Address(), call_base, setter_function, args);
				} else if (is_static) {
					GDScriptCodeGenerator::Address temp = codegen.add_temporary(static_var_data_type);
					if (assignment->use_conversion_assign) {
						gen->write_assign_with_conversion(temp, to_assign);
					} else {
						gen->write_assign(temp, to_assign);
					}
					gen->write_set_static_variable(temp, static_var_class, static_var_index);
					gen->pop_temporary();
				} else {
					
					if (assignment->use_conversion_assign) {
						gen->write_assign_with_conversion(target, to_assign);
					} else {
						gen->write_assign(target, to_assign);
					}
				}
				if (to_assign.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					gen->pop_temporary(); 
				}
				if (has_operation && assigned_value.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					gen->pop_temporary(); 
				}
				if (target.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
					gen->pop_temporary(); 
				}
			}
			return GDScriptCodeGenerator::Address();