Column "medium" is not created in table "referrers"

[medienbaecker]

First of all, thanks for this great plugin. I think it fits really nicely into the Kirby mindset 👍

I noticed my website did not track any referrers so I had a look at simplestats_errors.txt and saw hundreds of messages like General error: 1 table referrers has no column named medium. After editing the SQLite database and adding a medium column to the database it started working.

You'll probably have to add this to this line.

[Daandelange]

Hello, Thanks :)
Indeed, I forgot to add it. Thanks for the PR too. :)