The problem that I had today I had already had in the past, but, because I forgot the solution, I was here struggling another two hours or so. I was getting 0.0, for instance, as a chapter number.
To get rid of complications, I used sections instead of chapters when building my pages, but I then wanted to use Table of Contents to get a nice index.
That is how the problem appeared. The solution is quite easy, but it takes us a long time to get there on our own, is it not?
We just have to add this to the preamble:
And we then have to add this to the body: