Inline SVG images looks broken

[eiswind]

I found
#453

which introduced inline option for svg images.

but when I run my converter it fails with

Execution tts of goal org.asciidoctor:asciidoctor-maven-plugin:3.1.1:process-asciidoc failed: org.jruby.exceptions.NoMethodError: (NoMethodError) undefined method `read_svg_contents' for nil:NilClass -

Note that I'm running with jruby and asciidoctorj-revealjs 5.1.0. Can this be a problem with the jruby integration. It seems like the delegate converter is not set.

Any help would be appreciated.