### 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 (operand.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
				gen->pop_temporary();
			}
			return result;
		} break;
		case GDScriptParser::Node::ASSIGNMENT: {
			const GDScriptParser::AssignmentNode *assignment = static_cast<const GDScriptParser::AssignmentNode *>(p_expression);
			if (assignment->assignee->type == GDScriptParser::Node::SUBSCRIPT) {
				
				const GDScriptParser::SubscriptNode *subscript = static_cast<GDScriptParser::SubscriptNode *>(assignment->assignee);
#ifdef DEBUG_ENABLED
				if (subscript->is_attribute && subscript->base->type == GDScriptParser::Node::SELF && codegen.script) {
					HashMap<StringName, GDScript::MemberInfo>::Iterator MI = codegen.script->member_indices.find(subscript->attribute->name);
					if (MI && MI->value.setter == codegen.function_name) {
						String n = subscript->attribute->name;
						_set_error("Must use '" + n + "' instead of 'self." + n + "' in setter.", subscript);
						r_error = ERR_COMPILATION_FAILED;
						return GDScriptCodeGenerator::Address();
					}
				}
#endif
				
				StringName assign_class_member_property;
				GDScriptCodeGenerator::Address target_member_property;
				bool is_member_property = false;
				bool member_property_has_setter = false;
				bool member_property_is_in_setter = false;
				bool is_static = false;
				GDScriptCodeGenerator::Address static_var_class;
				int static_var_index = 0;