### 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
IdentifierNode *id = static_cast<IdentifierNode *>(p_previous_operand);
			switch (id->source) {
				case IdentifierNode::LOCAL_VARIABLE:
					source_variable = id->variable_source;
					id->variable_source->usages--;
					break;
				case IdentifierNode::LOCAL_CONSTANT:
					id->constant_source->usages--;
					break;
				case IdentifierNode::FUNCTION_PARAMETER:
					id->parameter_source->usages--;
					break;
				case IdentifierNode::LOCAL_ITERATOR:
				case IdentifierNode::LOCAL_BIND:
					id->bind_source->usages--;
					break;
				default:
					break;
			}
#endif
		} break;
		case Node::SUBSCRIPT:
			
			break;
		default:
			push_error(R"(Only identifier, attribute access, and subscription access can be used as assignment target.)");
			return parse_expression(false); 
	}
	AssignmentNode *assignment = alloc_node<AssignmentNode>();
	reset_extents(assignment, p_previous_operand);