fix: avoid unchecked nullptr deref on invalid lcms transform

[anthraxx]

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

[kornelski]

Thank you