Refactor modify_position pattern matching for ? operator.

The refactor should replace this [pattern matching](https://github.com/lambdaclass/yet-another-swap/blob/main/crates/yas_core/src/contracts/yas_pool.cairo#L645-L650) for the use of the ```?``` operator.
The idea is to test if it panics exactly the same way so we can be sure we maintain the same behavior.