if(!SvOK(MOUSE_xa_tc_code(xa))){
tc_code = mcall0s(tc, "_compiled_type_constraint");
av_store(xa, MOUSE_XA_TC_CODE, newSVsv(tc_code));
+
if(!(SvROK(tc_code) && SvTYPE(SvRV(tc_code)) == SVt_PVCV)){
mouse_throw_error(MOUSE_xa_attribute(xa), tc, "Not a CODE reference");
}