I mean we all sin, but say you get hit by a car after you just lie to someone, does that mean that person would go to hell?
I think the answer lies in the Church’s answer in the Catechism concerning those who commit suicide. This, of course, is a sin in which a person could die by the very act of committing a mortal sin (if some psychological condition didn’t remove their culpability).
This is what the Church says about that:
Suicide
2280 Everyone is responsible for his life before God who has given it to him. It is God who remains the sovereign Master of life. We are obliged to accept life gratefully and preserve it for his honor and the salvation of our souls. We are stewards, not owners, of the life God has entrusted to us. It is not ours to dispose of.
2281 Suicide contradicts the natural inclination of the human being to preserve and perpetuate his life. It is gravely contrary to the just love of self. It likewise offends love of neighbor because it unjustly breaks the ties of solidarity with family, nation, and other human societies to which we continue to have obligations. Suicide is contrary to love for the living God.
2282 If suicide is committed with the intention of setting an example, especially to the young, it also takes on the gravity of scandal. Voluntary co-operation in suicide is contrary to the moral law.
Grave psychological disturbances, anguish, or grave fear of hardship, suffering, or torture can diminish the responsibility of the one committing suicide.
2283 We should not despair of the eternal salvation of persons who have taken their own lives. By ways known to him alone, God can provide the opportunity for salutary repentance. The Church prays for persons who have taken their own lives.
In other words, it is possible that God could “provide the opportunity for salutary repentance” for someone who seems to us to have died not only in mortal sin but
by the very act of committing a mortal sin. The Church does not teach that anyone ought to presume that such an opportunity will be offered, since it is not for us to sit in judgment as if we were God to judge either in someone’s favor or against them, as we are not totally privy to the Divine Wisdom, Justice and Mercy. Having said that, however, the Church teaches that it is certainly OK to maintain the hope that some particular person who seems to have died in a lost state will be saved. The Church prays for such persons.
Accepting the Gospel, seeking baptism and availing ourselves of the life of the Church is the
normal way offered to us to seek the grace necessary for salvation. We should not be so presumptuous as to presume that we ourselves will be offered any other way. We should also not presume, however, that anyone else will not.