Linter: Usage of `.orNull` should be discouraged

[nbraud]

Expressions such as someOption.orNull currently compile without compiler warning. Such expressions might yield a null value, which will result in a NullPointerException later on.
Using someOption.get, which results in a NoSuchElementException at the point of error, should be preferred.

[iphydf]

.get should also be discouraged, as it causes exceptions, which we don't accept in production code. .fold or any of the other more specific methods or plain pattern matching or for-comprehensions should be preferred.

[nbraud]

Yes, the part about .get was meant for tests only. Thanks for clarifying.