Assertion error when using invalid values as class constant name

### Description

The following code:

```php
y::{5}::y;
```

```php
const y = y::{y};
```

Resulted in this output:
```
Termsig=6
```

But I expected this output instead:
```
Fatal error: Uncaught Error: Class "y" not found
```

```
Fatal error: Uncaught Error: Undefined constant "y"
```


### PHP Version

master

### Operating System

_No response_