[Wizdum]

The investigation revealed that the rocket (fired) because a freak surge of electricity jumped through the plane's system at the moment the pilot switched from the outside electrical generator to the plane's internal power system.
The voltage surged through five sequential safety devices designed to prevent just such a stray charge from reaching the rockets.

[rlmorel]

Truth is, it was wartime, and they found a shortcut (removing the safety pin) that saved an important amount of time and they decided up the chain (approved) that it was a risk worth taking for that time savings.

Remember, they were running high tempo combat operations; and that time saved by omitting that step counted when you were launching that many planes.

It just didn’t work out, and it cost them.

[Revski]

It was so and thanks for bringing it up. :)