<del>Strikethrough HTML</del> leads to crash

Crashing in

Lines 41 to 44 in f9b7be8

    
           let attributedString = try? NSAttributedString( 
        
               commonmark: markdownString, 
        
               attributes: attributes 
        
           )

or to be more exact in https://github.com/mattt/CommonMarkAttributedString/blob/578419f521d16fd5fb6e757e7f5a6a4748fc0c38/Sources/CommonMarkAttributedString/NSAttributedString%2BExtensions.swift#L35

I don't think this is due to the strikethrough, it also happens w/ other input. It is always useful to look at what the crash is ;-):

Thread 1: Simultaneous accesses to 0x107200e10, but modification requires exclusive access
And the concurrent access started in LayoutComputer.EngineDelegate.sizeThatsFits (presumably the SwiftUI layout).

It seems to be a weird interaction between WebKit (which is used for HTML parsing in NSAttributedString and seems to spin up a funky nested runloop?) and SwiftUI.

Actually it is probably "more complex HTML" which is piped through WebKit (maybe a " or <!-- also triggers this. I tried to replicate it in a test case, which doesn't raise. Because the SwiftUI is missing.

The case we are currently seeing is a message which contains "<name> changed". CommonMarkAttributedString tries to pipe this through NSAttributedString(...html) which produces the issue.
Which I suppose brings us full circle why we even parse the stuff as Markdown ;-) This <name> is verbatim content.

Fixed with #272.

	let attributedString = try? NSAttributedString(
	commonmark: markdownString,
	attributes: attributes
	)