[Bug] Monarch: Markdown syntax highlighting: continuation lines of list items rendered as code blocks

[kareldonk]

Reproducible in vscode.dev or in VS Code Desktop?

• Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

• Not reproducible in the monaco editor playground

Monaco Editor Playground Link

https://microsoft.github.io/monaco-editor/playground.html?source=v0.52.2#XQAAAAKiAQAAAAAAAABBqQkHQ5NjdMjwa-jY7SIQ9S7DNlzs5W-mwj0fe1ZCDRFc9ws9XQE0SJE1jc2VKxhaLFIw9vEWSxW3yscwzwauRgmSaumWUF-TBOsVJ4S4FwfCDQb5-2uUHXTVAefbVSd9IzaZ_vv9VR9KugsKihpSJZPgox8F4oW2m8J9KFw9qZvHqyprjcG0VSNk0LOjyrVa5ikwVDlGr-NibjN81Sv0qZtUJK-NhABGuhXGrUc_yjxpWm50luejDZ7T7BSnRqO7ZbC94w-ednXHeVtLBHEPsg4q99lYm-6ylvbElZl6ZR0jjH7_6HllAwXXHEiW3mrpiyJCdj5IyePrkvuUsw0O-7ryGNyj6VaD3nx4dESXVRAnRtItkQuEuyZGs_qUA6eu8n76CB_mAZ4-zEZVya_3bUyQuFKPzVqr5w6ZAM7-veK3

Monaco Editor Playground Code

Reproduction Steps

No response

Actual (Problematic) Behavior

There is an issue with syntax highlighting in case of Markdown files:

Continuation lines of list elements are highlighted as if they were code blocks, if the indentation is 4 spaces (3 spaces between the - and the text), or one tab:

List:

-   item1
-   item2
    continuation of item2

    paragraph, still part of the list item2

Not part of list.

In the Language Editor within the Monaco-Editor of the Monarch documention this is displayed as:

Monarch's language syntax definition for Markdown contains a rule for code blocks that renders indented lines (4 spaces or a tab) as string:

[
	// list (starting with * or number)
	[/^\s*([\*\-+:]|\d+\.)\s/, 'keyword'],

	// code block (4 spaces indent)
	[/^(\t|[ ]{4})[^ ].*$/, 'string']
]

This also explains why the effect is visible only if the indentation of the continuation lines is exactly 4 spaces or 1 tab, not if it is e.g. 3 spaces. Perhaps the grammar for lists would need to be more complex.
Lists can also contain sub elements such as paragraphs, tables, code blocks and nested lists etc.

Relates to: #2489

Expected Behavior

No response

Additional Context

monaco-editor version: 0.52.2