[cctbxbb] match_indices.paired_miller_indices() ungraceful overshoot

Hello all, I accidentally gave paired_miller_indices() a value > 1 for i_array, and got a segfault. The problem looks to be in match_indices.cpp, line 94: result.push_back(miller_indices_[i_array][pairs_[i][i_array]]); Maybe there should be a test that raises an exception on the python side, if possible. James