I made a mistake and let the builder run over my nether portal with a fortune quarry card, which turned all the blocks that formed the gate into dirt. Portal however still worked. (Purple portal blocks, dirt frame)

However when I /used/ said portal more out of a sense of morbid curiosity than anything, I spawned somewhere below the nether portal on the overworld and suffocated inside of a wall.

Very funny but likely not a simple fix nor really an issue, it's kind of intented :P