Bookworm does not show search results if the mobi book does not have a table of contents

[DraganRatkovich]

Describe the Problem

The title is enough, the mobi book does not show search results when the book has no table of contents. I have tried both English and Georgian books and the result is the same. It is enough to add at least one table of contents to the book, and the search results are again displayed without problems.

To Reproduce

1. Download archive containing two books in mobi format;
2. Open each file. The file names are enough to determine which ones contain a table of contents, open them individually, and search through the document.

You will notice that the search results will be empty in a document that does not contain a table of contents.

It's also worth noting that this problem only occurs in .mobi books, epub doesn't have this problem, tested them both with and without a table of contents, everything works quite well.

Expected behavior

The bookworm should display search results in both types of documents.

If the problem is related to a file, indicate the file you have opened

Documents.zip

Desktop (please complete the following information):

• OS: Windows 10 21 H2
• Bookworm version Latest, downloaded from AppVeyor
• Recent settings you may have changed in Bookworm None