Fixes that
```
Pattern {
let tuple = (attr<"3 : i34">);
not tuple.0;
erase _;
}
```
would crash the PDLL parser because it expected a native constraint
after `not`.
Fixes that
```
Pattern {
let tuple = (attr<"3 : i34">);
not tuple.0;
erase _;
}
```
would crash the PDLL parser because it expected a native constraint
after `not`.