At first I wasn't so keen on this change, as it's common for the first argument of most BKE_* functions that take ID data-blocks as their first argument to have non-null arguments.

However accessing the size & aspect allows a NULL image which use useful fallback values, so this seems like a case where a default fallback in the case of a null image is reasonable too.

Accepting, although the patch subject & description need to be updated. The TODO should be either removed or expanded on (explaining why it is buggy).