Rogue One filled one of the biggest plot holes from Star Wars Episode 4, by showing that the exhaust port was designed as a weak spot of the Death Star by its architect Galen Erso.
Was the idea that someone intentionally designed a weak spot so that the Death Star could be destroyed an invention of the writers of Rogue One or was it an idea that George Lucas came up with but that was never revealed? (or was it?)
Are there sources that confirm that and show who came up with that idea?