Added a sanity check on gmf_data/data nbytes
Added a sanity check on gmf_data/data nbytes


Former-commit-id: 701e859c1d3f1337743d82dd2e6966f954c52aa2 [formerly 701e859c1d3f1337743d82dd2e6966f954c52aa2 [formerly 62f1d443bbf92ceba9fc59c1928adecbb5b6f842]]
Former-commit-id: 1fc7be3ada116b9026922339011c1efd962a9cca
Former-commit-id: 88b5cdb72147c73d572c0da94faa252d7c6128f4
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine