The idea of error log was not only for helping to find error cause and repair it in the first model but also for finding weakness points in design (mechanical, electrical, software, EMI protection,..)
all very good, but still wrong.

Succesful testing does not prove the abscence of bugs, it proves the abscence of known bugs.

The only way to not have "weaknesses" is by design, not by throwing something together and start testing.

I have seen bugs that did not show for a full year!

Erik