undefined method `decls' for nil:NilClass (NoMethodError)

[nullnull]

What is the problem?

When analyzing ActiveRecord children class with rbs_rails outputs, this error has occured.

$ typeprof gem_rbs/gems/**/*.rbs sig/rbs_rails**/*.rbs app/models/post.rb -o sig/post.rbs
/Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/import.rb:262:in `each_class_decl': undefined method `decls' for nil:NilClass (NoMethodError)
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/import.rb:113:in `conv_classes'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/import.rb:80:in `dump_json'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/import.rb:69:in `load_rbs'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/import.rb:48:in `load_path'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/import.rb:481:in `import_rbs_file'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/config.rb:100:in `block in analyze'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/config.rb:96:in `each'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/lib/typeprof/config.rb:96:in `analyze'
	from /Users/foo/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/typeprof-0.11.0/exe/typeprof:6:in `<top (required)>'
	from /Users/foo/.rbenv/versions/3.0.0/bin/typeprof:23:in `load'
	from /Users/foo/.rbenv/versions/3.0.0/bin/typeprof:23:in `<main>'

Steps to Reproduce

Please setup this minimum rbs_rails sample, and run typeprof gem_rbs/gems/**/*.rbs sig/rbs_rails**/*.rbs app/models/post.rb -o sig/post.rbs.
https://github.com/nullnull/rails_with_rbs_rails_sample

Versions

$ typeprof --version
typeprof 0.11.0

Other

Thanks for developing cool library!