message: check vector emptiness before access it
diff: @@ -1265,12 +1265,15 @@ struct Net::Impl
  ld.outputBlobsWrappers = layers[lpNext.lid].outputBlobsWrappers;
  if ( preferableTarget == DNN_TARGET_OPENCL )
  + {
  + if ( !activData->consumers.empty() )
  {
  nextData = &layers[activData->consumers[0].lid];
  lpNext = LayerPin(activData->consumers[0].lid, 0);
  }
  }
  }
  + }
  // fuse convlution layer followed by eltwise + relu
  if ( preferableTarget == DNN_TARGET_OPENCL )
  