### Godot version

v4.0.beta14.official [28a24639c]

### System information

MacOS 12.6.2

### Issue description

Beta 14 throws an error for custom `@icon`, e.g.
```
class_name StateMachine extends Node

@icon("res://assets/icons/state_machine.svg")
```
> Annotation "`@icon`" is not allowed in this level.

In beta 13 and before that worked fine.

### Steps to reproduce

1. Add a custom `@icon` in a custom node script.
2. Error message: Annotation "`@icon`" is not allowed in this level.

There are possibly other errors because a `class_name` node is now not recognized if extended by other classes, but they should resolve if `@icon` is removed.

### Minimal reproduction project

N/A
GDScriptTokenizer::Token::Type op_type = previous.type;
	UnaryOpNode *operation = alloc_node<UnaryOpNode>();
	switch (op_type) {
		case GDScriptTokenizer::Token::MINUS:
			operation->operation = UnaryOpNode::OP_NEGATIVE;
			operation->variant_op = Variant::OP_NEGATE;
			operation->operand = parse_precedence(PREC_SIGN, false);
			if (operation->operand == nullptr) {
				push_error(R"(Expected expression after "-" operator.)");
			}
			break;
		case GDScriptTokenizer::Token::PLUS:
			operation->operation = UnaryOpNode::OP_POSITIVE;
			operation->variant_op = Variant::OP_POSITIVE;