Leaderboard Edit Page

[TheTedder]

There must be a leaderboard edit page that lives at /leaderboard/{id}/edit where {id} is a long integer. If the id route parameter does not correspond to an existing (including deleted) leaderboard, the page must display "leaderboard does not exist."
There must be a back button at the top of the page content that takes the user to the leaderboard view page when clicked. If the user has unsaved changes, they are given a confirmation prompt before navigating away.
The page must display the leaderboard's fields the same as the leaderboard view page except instead of text, the leaderboard's name, slug, and info will be text input form fields. The name and slug must be short text input (<input type="text">) and the info must be long text input (<textarea>). The text fields must begin populated with the existing values that the leaderboard has for them
There must be a "save" button below the leaderboard edit form. Clicking on this button submits the changes the user has made. If the changes are accepted, the user is returned to the leaderboard view page. If the changes are not accepted, an error is displayed.