That one blocked off door in Sootopolis. There's nothing there, why not finish the wall so I don't think there's something there!?!Here
Here
blocked door (https://m.youtube.com/watch?v=M3muhUcdbyU)
Explanation of the crash from the comments
"In the Japanese versions, the room was supposed to be the place where you could battle trainers who you scanned in with the E-Reader accessory. However, in the US version, E-Reader functionality was abandoned due to the fact that the E-Reader was a commercial failure in the 'States. The game displays odd text and crashes because it tries to access a nonexistent memory location normally reserved for the E-Reader. Since there is no written data in that location, whatever the game displays is completely random and often uninterpretable by the game, and so it crashes."
The problem is it's blocked off with potted plants rather than properly sealed.That's because they most likely had a very limited time to translate and whatever else to the game, they didn't have time to get rid of the door and replace it with a wall, so just put some plants instead.