Crash in compiling ISO 10303-104 with PNG images

[ronaldtse]

This issue comes from https://github.com/metanorma/iso-10303/pull/31 .

There is an issue in compiling the document:

At this node,

==============================ERROR AT NODE
<p id="_0fe3408a-a082-4d10-b88b-fd419efa2dd8"><xref target="fig-express-g-diagram-1" type="inline"/> through <xref target="fig-express-g-diagram-86" type="inline"/> correspond to the EXPRESS listing given in <xref target="annex-computer-interpretable-listings" type="inline"/>. The diagrams use the EXPRESS-G graphical notation for the EXPRESS language. EXPRESS-G is defined in annex D of <xref target="iso10303-11" type="inline"/>.</p>
<figure id="fig-express-g-diagram-1">
<name>Structural response definition schema EXPRESS-G diagram, 1 of 86.</name>
<image src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAApUAAANYCAYAAACVUBZ5AAAACXBIWXMAAB2HAAAdhwGP5fFlAAAAGXRFWHRTb2Z0d2FyZQB3d3cuaW5rc2NhcGUub3Jnm+48GgAAIABJREFUeJzs3XmYTvX/x/HXmM0MY9+LqBRlKyQhKkLakCJZy1rflAiNn
...
</figure>
<figure id="_51e48819-aeb3-44eb-94ac-b1f6a17036d8">
<name>Structural response representation schema EXPRESS-G diagram, 2 of 86.</name>
...
</figure>
<figure id="fig-express-g-diagram-86">
<name>Scalar vector tensor schema EXPRESS-G diagram, 86 of 86.</name>
<image src="data:image/png;base64,iVBORw0...uQmCC" id="_a023e991-372c-4463-8b37-97bc6d348428" mimetype="image/png" height="auto" width="auto"/>
</figure>

Metanorma compile crashes with this message:

bundler: failed to load command: metanorma (/Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/bin/metanorma)
RuntimeError: error parsing fragment (1)
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/node.rb:476:in `in_context'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/node.rb:476:in `parse'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/document_fragment.rb:19:in `initialize'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/document.rb:235:in `new'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/document.rb:235:in `fragment'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/builder.rb:354:in `<<'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/bundler/gems/metanorma-standoc-c9185279bb8e/lib/asciidoctor/standoc/section.rb:136:in `block in annex_parse'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/builder.rb:394:in `insert'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/nokogiri-1.10.9/lib/nokogiri/xml/builder.rb:377:in `method_missing'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/bundler/gems/metanorma-standoc-c9185279bb8e/lib/asciidoctor/standoc/section.rb:133:in `annex_parse'
  /Users/me/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/bundler/gems/metanorma-iso-da7f9147dc47/lib/asciidoctor/iso/section.rb:31:in `block in section'

I wonder if this is due to the size of the node, or some issue with parsing? It looks correct to me, though.

[ronaldtse]

Related to sparklemotion/nokogiri#1442

[ronaldtse]

Since this is due to size of node content caused by images, we can:

1. Do not dereference images when parsing. Only dereference them into base64 when the document is completed.
2. Fix our usage of "adding nodes" so that Nokogiri doesn't break.

[opoudjis]

Doing the first works for the given issue.

Not clear to me what to do to error-proof "<<"; any rescue would still result in either an incomplete or an empty document.