HW: OSX 10.9.5
SW: OpenSC 0.14.0 - built from source
Reader: Castle EZ100PU + manufacturer drivers

Once Firefox has been set up to use the opensc-pkcs11.so as a security device provider, inserting a non-PKCS#11 card in the reader causes a crash in sc_pkcs11_get_mechanism_list, as it will be called with a NULL sc_pkcs11_card. I haven't spent much time debugging the issue but it seems like either slot_allocate doesn't assign sc_pkcs11_slot->card, or pkcs15_create_slot is invoked with a NULL sc_pkcs11_card instance.