The HTML Processor internally throws an exception when it reaches HTML
that it knows it cannot process, but this exception is not made
available to calling code. It can be useful to extract more knowledge
about why it gave up, especially for debugging purposes.
In this patch, more context is added to the WP_HTML_Unsupported_Exception
and the last exception is made available to calling code through a new
method, `get_unsupported_exception()`.
Developed in https://github.com/WordPress/wordpress-develop/pull/6985
Discussed in https://core.trac.wordpress.org/ticket/61646
Props bernhard-reiter, dmsnell, jonsurrell.
See #61646.
Built from https://develop.svn.wordpress.org/trunk@58714
git-svn-id: http://core.svn.wordpress.org/trunk@58116 1a063a9b-81f0-0310-95a4-ce76da25c4cd
4f85cc258c