Fixed a long-hunted bug:
Fixed a long-hunted bug:

Markdown-it creates pathological cases in some valid but less usual usual use cases, such as: paragraph in next line after heading, HTML comment before heading, end-of file at the end line of a paragraph following some heading... In such cases, redundant md.renderer.rules.heading_open call take place, with non-existing heading id.
Solution: check-up and return added.

SAKryukov/vscode-markdown-to-html