After messing up at work by calling in sick way beyond the assigned time (my day starts at 9, and I called in at 11) I got a stern talk with my boss and senior programmer. My boss was ready to fire me and had the paper ready and on the table but the senior convinced him not to.

As I was at the end of my contract my boss offered me a new contract but wanted to have ability to fire me directly if he seemed necessary, so he asked me to sign a resignation letter without a date on it. I have not done this yet. Is this a normal practice and should I even sign something like that as it seems very dangerous from my side.

I work at a small IT company of 5 people in Europe so we don't have an HR or really any dedicated people for this kind of thing.

This is my first job and I have worked here for 7 months and for about 4 months internship before that.