Query strings and type safety
Query strings are usually strings, but - as some might not be aware of - can also be quite easily an array. So not checking on the type and blindly using it in stringish operations can currently cause undesired results.
$result = 'string' . $this->request->getQuery('key'); // Dangerous without checking if set and a string
So with the current implementation of how query strings (and named params) work, one should always assert the correct type first: