fix: avoid unchecked nullptr deref on invalid lcms transform

fix: avoid unchecked nullptr deref on invalid lcms transform

On invalid data the requested transform from lcms may return nun
successfully. Hence we need to check the return value and early
the function to avoid a segfault.
To distinguish the concrete error, a new error code (45) has been
introduced.

Signed-off-by: Levente Polyak <levente@leventepolyak.net>