midgard_object_list: set NOT_EXIST error and return NULL when ID is 0. Fixes #110
midgard_object_list: set NOT_EXIST error and return NULL when ID is 0.
Fixes #110

midgardproject/midgard-core,piotras/midgard-core,midgardproject/midgard-core,midgardproject/midgard-core,piotras/midgard-core,midgardproject/midgard-core,piotras/midgard-core,piotras/midgard-core