I think you should treat this as an extra person on field of play because there are no sanctions listed in LOTG for the substitution procedure not being followed correctly only what to do about extra persons, of which named subs are specifically covered. Sub law 7 covers what to do in the event of substitute (extra player) entering without permission and interfering (DFK/PK) and sub law 9 if a goal is scored (GK, CK, or DB).
If a substitute enters w/o permission play is only stopped if he interferes or a goal is scored with the extra person on FOP. And in that case the restarts are direct or as otherwise described if a goal is scored. No IDFKs.
Happy to be corrected but that is how I read law 3.