Infinite loop in lalr and cyk

This is the shortest I managed to get the grammar. No idea what's causing the infinite loop, but notably it only happens when I set the priority `start.1`. Without that it throws a `GrammarError`.

```py
Lark(
    'start.1: "a" | start start*',
    parser='lalr'
).parse('aa')
```

I get the same issue in `cyk` but not `earley`.
