The problem of bug "select struct switch type var" when trying to build a book with its own functions *.md.

[ghost]

Why, after the Jupiter-book build command in the user interface, instead of my files section_1 md, section_2 md specified in the _toc.yml module, the message appears: select struct switch type var. At the same time, the file markdown is displayed. What does this phrase mean: select struct switch type var?
title:
_config.yml
title: DATA STRUCTURES AND ALGORITHMS.HYBRID IMPLEMENTATION (DRAKON + GOLANG)
author: Ivanov S.A.
logo: logo.png

Force re-execution of notebooks on each build.

See https://jupyterbook.org/content/execute.html

execute:
execute_notebooks: auto

Add a bibtex file so that we can create citations

bibtex_bibfiles:

• references.bib
  _toc.yml
  format: jb-book
  root: intro
  chapters:
• file: section_1.md
• file: section_2.md
• file: section_3.md