Code fenced blocks are not processed properly

[fourdim]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and couldn’t find anything (or linked relevant results below)

Affected packages and versions

15.0.1

Link to runnable example

https://stackblitz.com/edit/github-dbrz8s?file=src%2Fmain.ts

Steps to reproduce

// https://spec.commonmark.org/0.31.2/#example-138

const sourceMarkdown = `
~~~ ~~~
aaa
`;

Expected behavior

Code fences (opening and closing) cannot contain internal spaces or tabs.

Actual behavior

Parsing ~~~ as language.

Runtime

No response

Package manager

No response

OS

No response

Build and bundle tools

No response

[wooorm]

The CM example you reference is different, it uses backticks.
Backticks and tildes are different. Because backticks are resused for “inline” code as well.

https://spec.commonmark.org/dingus/?text=~~~%20~~~%0Aaaa