Cannot read property 'level' of undefined

[jesobreira]

Bug Report

Steps to reproduce

Run the following README.md:

# Heading 1

Test

## Heading 2

### Heading 3A

Lorem ipsum

#### Heading 4A

##### Heading 5A

Lorem ipsum

### Heading 3B

Lorem ipsum

#### Heading 4B <!-- {docsify-ignore} -->

##### Heading 5B

Lorem ipsum

What is current behaviour

The sidebar does not show up and the console shows:

```docsify.min.js:1 Uncaught TypeError: Cannot read property 'level' of undefined
    at $n.sidebar (docsify.min.js:1)
    at Vn.Xn._renderSidebar (docsify.min.js:1)
    at Vn.Pn (docsify.min.js:1)
    at docsify.min.js:1
    at o (docsify.min.js:1)
    at B (docsify.min.js:1)
    at t (docsify.min.js:1)
    at docsify.min.js:1
    at docsify.min.js:1
    at docsify.min.js:1

What is the expected behaviour

Sidebar shows up

Other relevant information

• Bug does still occur when all/other plugins are disabled?

• Your OS: macOS Catalina

• Node.js version: 12.18.3

• npm/yarn version: 6.14.6

• Browser version: Chrome Version 84.0.4147.135 (Official Build) (64-bit)

• Docsify version: 4.11.6

• Docsify plugins: none

Please create a reproducible sandbox

Mention the docsify version in which this bug was not present (if any)

[sy-records]

I can't reproduce your question.

The README.md will not show up in the sidebar, you need to add - [README](README.md) to _sidebar.md

[sy-records]

#1355 (comment) As with this one, you need to add configuration items.

Cannot read property 'level' of undefined

This is an exception message that we can optimize

[jesobreira]

I'm not using a custom _sidebar.md, rather I'm trying to use the auto-generated table of contents. Does it make any difference?

[sy-records]

No problem, here's a bug.