Mermaid diagrams not rendering when page is titled Mermaid

[FISHMANPET]

Contribution guidelines

• I've read the contribution guidelines and wholeheartedly agree

I've found a bug and checked that ...

• ... the problem doesn't occur with the mkdocs or readthedocs themes
• ... the problem persists when all overrides are removed, i.e. custom_dir, extra_javascript and extra_css
• ... the documentation does not mention anything about my problem
• ... there are no open or closed issues that are related to my problem

Description

Pages with the title of Mermaid or mermaid (as defined via the top level header in the md file) do not render mermaid diagrams. If the filename is mermaid.md and no header is defined in the file, the mermaid diagram will render.

Expected behaviour

Mermaid diagrams render on pages titled "Mermaid"

Actual behaviour

Mermaid diagrams do not render on pages titled "Mermaid"

Steps to reproduce

I've created a minimal site that demonstrates the behavior: https://github.com/FISHMANPET/mkdocs-mermaid
I've also hosted it on a webserver, because when you view it that way (rather than mkdocs serve) you will see errors in the browser developer console as well:

Package versions

• Python: 3.9.5
• MkDocs: 1.2.3
• Material: 8.2.3

Configuration

# https://github.com/FISHMANPET/mkdocs-mermaid/blob/main/mkdocs.yml
site_name: My Docs
theme:
  name: material
markdown_extensions:
  - pymdownx.superfences:
      custom_fences:
        - name: mermaid
          class: mermaid
          format: !!python/name:pymdownx.superfences.fence_code_format

System information

• Operating system: Windows 10
• Browser: Chrome 98

[squidfunk]

Thanks for reporting. Exact duplicate of #3596. Explanation and mitigation in #3596 (comment).

Additionally see https://twitter.com/squidfunk/status/1495839268182409216

[squidfunk]

@FISHMANPET Funny. After I've read your tweet, I actually came up with a way to fix it, and it's quite simple. The reason is that while reading about this behavior, I realized that we could just add a simple check to mitigate the problem at hand, so it's fixable after all. Sometimes a little time to think about stuff or learn works wonders. Fixed in cfa6474.