* For some reason cppcheck complains with `fp != nullptr` but accepts truthiness
of handle by itself.
* Note that the expressions are equivalent according to the C++ standard ("A
prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member
type can be converted to a prvalue of type bool. A zero value, null pointer
value, or null member pointer value is converted to false; any other value is
converted to true. A prvalue of type std::nullptr_t can be converted to a
prvalue of type bool; the resulting value is false.")
Peter Duerr