Someone else’s Github account got linked to mine, and I get an error when trying to fix it up

I created an account and opted to use the GitHub option for signing up. Unfortunately another user was logged into GitHub on another tab and the system used those credentials rather than mine. We are trying to switch the accounts over, but when I try to reenable the GitHub authorization, the process goes into limbo.

Here is the text of one error I get:

Application error The OpenStreetMap server encountered an unexpected condition that prevented it from fulfilling the request (HTTP 500)     Feel free to contact the OpenStreetMap community if your problem persists. Make a note of the exact URL / post data of your request. This may be a problem in our Ruby On Rails code. 500 occurs with exceptions thrown outside of an action (like in Dispatcher setups or broken Ruby code)