Not sure if keeping these checks here makes sense - this function as well as `as_release_to_xml_node` and `as_release_load_from_yaml` and `as_release_emit_yaml` are internal functions that are called thousands of times in many occasions and have all their input verified already. Then again, the extra checks will most likely not slow these functions down by any noticeable amount (but if any of these checks would ever trigger it would be a fatal error anyway).

Spurious newline.

I don't think this check is needed here: It is used in a static and internal function, so the input will already have been verified, and a hard `g_assert` will be compiled out in all builds that aren't debug builds anyway.

nit: For these one-line return/set functions with just one obvious check, I think you can just drop the two empty lines, they just add visual noise.