I don’t think it would be possible in that case, unless the error happened in a script that is located in the player’s character or player’s player instance. Which if it did, I’m not sure if the server would detect it if thE error happened locally (from localscript) and you would need some string pattern stuff
It could either be a client sided MessageOut that fires a RemoteEvent with the information to then send as a webhook.
OR
They looked through all the players in game and checked if any of their name was mentioned anywhere in the error to figure out the player that got the error if it was server sided