Toyota lost the lawsuit on their development processes and firmware design. As far as I know, no specific bug that would cause unintended acceleration was ever found.
I truly believe that it was human factors and not a computer failure.
I've been in similar situations and had a acquaintance drive through a wall because of human factors. In our case, the parking lot was relatively flat but had a drainage channel at the front. So, you could put your car into reverse, release the brake, and your car would roll forward. Quite unnerving if you are driving a stick, but your brain processes it because you are used to rolling in the wrong direction. If you are driving an automatic, you smack the accelerator, jump across way too small gap between you and a building, and bury your car trunk in an office wall.
Nevertheless, I'm also quite happy that Toyota got smacked as their development process was TERRIBLE. They 100% deserved what they got even if it wasn't a computer bug.
(and was only a problem because they didn't handle critical variables correctly, by having mirrors of the values that could be compared to protect against various types of corruption)
The material from Barr is worth reading too (google it), and if you want some amusement:
https://www.embedded.com/why-every-embedded-software-develop...
https://www.embedded.com/a-rebuttal-to-why-every-embedded-so...