Improved an error message
Improved an error message


Former-commit-id: e9d3d5be16762bee55f51fb2f6906a03dc6993e5 [formerly e9d3d5be16762bee55f51fb2f6906a03dc6993e5 [formerly 17f8a7cf06855c5d95bb1de9262524aabaa7cb42]]
Former-commit-id: 220b82c928fb908cd782476163d149f89e608eb9
Former-commit-id: d64f33ed14bffe29167299833cb3ec259d7ced8a
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine