Default initialization produces DR_ASSERT each time because drmgr_get_emulated_instr_data retruns false in this case
...
} else if (drmgr_is_emulation_start(instr)) {
bool ok = drmgr_get_emulated_instr_data(instr, &emulation_info);
DR_ASSERT(ok);
...
DR_EXPORT
bool
drmgr_get_emulated_instr_data(instr_t *instr, emulated_instr_t *emulated)
{
ASSERT(instr_is_label(instr), "emulation instruction does not have a label");
ASSERT(drmgr_is_emulation_start(instr), "instruction is not a start emulation label");
if (emulated->size < offsetof(emulated_instr_t, flags))
return false;
...