One problem i see with spacex is their propulsive landing feature. What if things go wrong at that point, like a software or a sensor problem causing it to desc

One problem i see with spacex is their propulsive landing feature. What if things go wrong at that point, like a software or a sensor problem causing it to descend at a speed too high/not realizing it approaches the surface/just hovering and expending the propelland quickly? If landing on land, they don't have any backup, and astronauts are doomed, falling from even very low altitude (30-50ft) will be fatal.