bug(turndown-plugin-gfm): incompatible with original turndown

[flaviut]

Operating system

macOS

Joplin version

n/a

Desktop version info

n/a

Current behaviour

This commit 832e945
adds a new function to turndown - 832e945#diff-582d99eae9ac2e71f31737a47dcffa472aa1932ce7a04a78608f11c368406bbbR150
then references the function here: 832e945#diff-0d19da1f333aad24ea14096ec7f96319837830a1b9398112215a9ec9d40d9b81R226
and finally here: 832e945#diff-0d19da1f333aad24ea14096ec7f96319837830a1b9398112215a9ec9d40d9b81R164

But, that function is not available if using @joplin/turndown-plugin-gfm, resulting in the following exception:

readerMode.bundle.js:50248 TypeError: isCodeBlock_ is not a function
    at nodeContains (readerMode.bundle.js:218:29)
    at tableShouldBeHtml (readerMode.bundle.js:247:10)
    at Object.filter (readerMode.bundle.js:127:42)
    at filterValue (readerMode.bundle.js:88022:16)
    at findRule (readerMode.bundle.js:88010:9)
    at Rules.forNode (readerMode.bundle.js:87995:17)
    at TurndownService.replacementForNode (readerMode.bundle.js:88528:25)
    at readerMode.bundle.js:88493:40
    at NodeList.reduce (<anonymous>)
    at TurndownService.process (readerMode.bundle.js:88486:17)

Expected behaviour

Proposed solutions:

1. Document clearly that @joplin/turndown-plugin-gfm is not compatible with the original turndown and that @joplin/turndown should be used instead
2. Maintain compatibility with turndown. In this case it is quite simple - replace the function call with conditional function call isCodeBlock_?.(child). Thougho there cases (if there are any) might not be as simple

Logs

No response

[flaviut]

Dupe of #9881

[laurent22]

A pull request for this would be welcome, especially if you've already identified where the problem is in the code