Newbie: TOC duplicating and HTML errors? (Related? Maybe not? Help!)
I'm at the final step of my first-ever InDesign epub export and I'm running into a maddening issue.
When I create my table of contents, it's pulling from a single header style, as shown here:

The header style is only used at the beginning of each chapter. Nowhere else.
Upon export, my epub is giving me the following error in Sigil:

I'm guessing this is related to the other part of my problem, which is that the table of contents in the exported epub is creating entries for every single page. Here it is in Adobe Digital Editions.

I have no idea what to do. I don't even know if these two problems are actually related, or if they're two separate issues. I've been following along with this tutorial: https://www.youtube.com/watch?v=xkRp7fyP6KM
And I used this tutorial for the TOC specifically: https://www.youtube.com/watch?v=zRD6wHc14S0
Help very very appreciated! This book is for a client, so unfortunately I can't share files, but I am happy to screenshot any settings menus etc. if you tell me where to go.
