### Godot version

3b086aa06

### System information

ArchLinux x11

### Issue description

```gdscript
extends Node

@export_group("My Properties")
@export var number = 3
@export var string = ""

@export_group("Prefixed Properties", "prefix_")
@export var prefix_number = 3
@export var prefix_string = ""

@export_group("", "")
@export var ungrouped_number = 3
```

![image](https://user-images.githubusercontent.com/70787919/214983963-528c415b-745b-47fc-9777-36ebe31a3060.png)


### Steps to reproduce

- create script
- @export_group
- go inspector

### Minimal reproduction project

‮
ClassNode *n_class = alloc_node<ClassNode>();
	ClassNode *previous_class = current_class;
	current_class = n_class;
	n_class->outer = previous_class;
	if (consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected identifier for the class name after "class".)")) {
		n_class->identifier = parse_identifier();
		if (n_class->outer) {
			String fqcn = n_class->outer->fqcn;
			if (fqcn.is_empty()) {
				fqcn = script_path;
			}
			n_class->fqcn = fqcn + "::" + n_class->identifier->name;
		} else {
			n_class->fqcn = n_class->identifier->name;
		}
	}
	if (match(GDScriptTokenizer::Token::EXTENDS)) {
		parse_extends();
	}
	consume(GDScriptTokenizer::Token::COLON, R"(Expected ":" after class declaration.)");
	bool multiline = match(GDScriptTokenizer::Token::NEWLINE);
	if (multiline && !consume(GDScriptTokenizer::Token::INDENT, R"(Expected indented block after class declaration.)")) {
		current_class = previous_class;
		complete_extents(n_class);
		return n_class;