Having trouble with StaticFile object and output

[Fred Cassirer]

I am getting faults from indexer.rb when trying to process JekyllStaticFile objects. Specifically, on this line:

  137:  items.select! {|i| output_ext(i) == '.html' && ! @excludes.any? {|s| (i.url =~ Regexp.new(s)) != nil } }

which calls

def output_ext(doc)
        if doc.is_a?(Jekyll::Document)
          Jekyll::Renderer.new(@site, doc).output_ext
        else
          doc.output_ext
        end
      end

The problem appears to be that there are some Static files that do not have the output_ext method: and doc.output_ext raises an exception.
Note that the static file is a .PNG file (I put this in the excludes in my _config.yml, but that doesn't seem to work ...)
If I ignore the exception, it fails later on some creates. It appears that there have been changes in Jekyll 3.0.0 (I'm using 3.0.1 but it fails the same in 3.0.0) around the handling of the output_ext, but it isn't clear if this is the cause.

The 2nd exception is:
search_entry.rb:16:in `create': Not supported (RuntimeError)

Again, the object for 'page_or_post' is a Jekyll::StaticFile
Am I missing something basic?

Thanks in advance for any insight.
-Fred

A closer look from a debug session:

first, list out the items variable:

[3] pry(#Jekyll::LunrJsSearch::Indexer)> items
 Jekyll:Page @name="404.md",
 Jekyll:Page @name="about.md",
 ...
 Jekyll::Document _design/simon/simon_design.md collection=design,
...
Jekyll::StaticFile:0x00000003682790
...

Jekyll::StaticFile does NOT have an output_ext method
[3]  ls items[28]
Jekyll::StaticFile#methods:
  defaults     destination_rel_dir  modified?      mtime  placeholders   to_liquid  url    write?
  destination  extname              modified_time  path   relative_path  type       write
instance variables: @base  @collection  @dir  @extname  @name  @relative_path  @site
class variables: @@mtimes

Jekyll::Documents has a output_ext method
[4] pry(#)> ls items[27]
Comparable#methods: <  <=  ==  >  >=  between?
Jekyll::Document#methods:
  <=>                    collection         extname                next_doc          populate_categories  relative_path        trigger_hooks
  []                     content            generate_excerpt?      output            populate_tags        render_with_liquid?  url
  asset_file?            content=           id                     output=           post_read            respond_to?          url_placeholders
  basename               data               inspect                output_ext        previous_doc         sass_file?           url_template
  basename_without_ext   date               merge_data!            path              published?           site                 write
  cleaned_relative_path  destination        merged_file_read_opts  permalink         read                 to_liquid            write?
  coffeescript_file?     excerpt_separator  method_missing         place_in_layout?  related_posts        to_s                 yaml_file?
instance variables:
  @basename              @cleaned_relative_path  @content  @extname          @output_ext  @relative_path  @to_liquid
  @basename_without_ext  @collection             @data     @has_yaml_header  @path        @site           @url
[5] pry(#)> ls items[0]
Jekyll::Convertible#methods:
  []                  converters  invalid_layout?        place_in_layout?  render_all_layouts   sass_file?  transform
  asset_file?         do_layout   merged_file_read_opts  published?        render_liquid        to_liquid   type
  coffeescript_file?  hook_owner  output_ext             read_yaml         render_with_liquid?  to_s        write
Jekyll::Page#methods:
  basename   content   data   destination  dir=  ext=   index?   name   output   pager   path       process        render  site=     url
  basename=  content=  data=  dir          ext   html?  inspect  name=  output=  pager=  permalink  relative_path  site    template  url_placeholders
instance variables: @base  @basename  @content  @converters  @data  @dir  @ext  @name  @site  @url

[Jonathan McCaffrey]

I think I just created a fix for this as I saw the same issue

#92