The following error has been occurred when running bundle exec metanorma site generate.
.rbenv/versions/3.1.5/lib/ruby/gems/3.1.0/gems/relaton-plateau-1.19.2/lib/relaton/plateau/bibitem.rb:47:in `block (2 levels) in to_xml': undefined method `to_xml' for nil:NilClass (NoMethodError)
cover.to_xml b
^^^^^^^
Did you mean? to_yaml
The following error has been occurred when running
bundle exec metanorma site generate
.