Dereference before null check

There may be a null pointer dereference, or else the comparison against null is unnecessary. All paths that lead to this null pointer comparison already dereference the pointer earlier
/src/block_cache/block_io.c:416: REVERSE_INULL 168237 Directly dereferencing pointer "dsk".
/src/block_cache/block_io.c:423: REVERSE_INULL 168237 Null-checking "dsk" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.