measureCoaddSources can hit an assertion failure in GalSim:

python: src/hsm/PSFCorr.cpp:731: void galsim::hsm::find_ellipmom_1(galsim::ConstImageView<double>, double, double, double, double, double, double&, double&, double&, double&, double&, double&, double&, boost::shared_ptr<galsim::hsm::HSMParams>): Assertion `iy1 <= iy2' failed.

This is due to GalSim using asserts rather than throwing an exception. We fixed this on the HSC side (7a73869), but it didn't come over because we're using GalSim as a dependency rather than sucking it into the package.

I thought I reported this upstream at one point...