Render blob viewer error

app/helpers/blob_helper.rb

@@ -217,4 +217,13 @@ module BlobHelper
   def open_raw_file_button(path)
     link_to icon('file-code-o'), path, class: 'btn btn-sm has-tooltip', target: '_blank', rel: 'noopener noreferrer', title: 'Open raw', data: { container: 'body' }
   end
+
+  def blob_render_error_reason(viewer, error)
+    case error
+    when :too_large
+      "it is larger than #{number_to_human_size(viewer.relevant_max_size)}"
+    when :server_side_but_stored_in_lfs
+      "it is stored in LFS"
+    end
+  end
 end

app/views/projects/blob/_render_error.html.haml

+- reason = blob_render_error_reason(viewer, error)
+
+- options = []
+- if error == :too_large && viewer.can_override_max_size?
+  - options << link_to('load it anyway', url_for(params.merge(viewer: viewer.type, override_max_size: true, format: nil)))
+- if viewer.rich? && viewer.blob.rendered_as_text?(override_max_size: true)
+  - options << link_to('view the source', '#', class: 'js-blob-viewer-switcher', data: { viewer: 'simple' })
+- options << link_to('download it', blob_raw_url, target: '_blank', rel: 'noopener noreferrer')
+
+.file-content.code
+  .nothing-here-block
+    The #{viewer.switcher_title} could not be displayed because #{reason}.
+
+    You can
+    = options.to_sentence(two_words_connector: ' or ', last_word_connector: ', or ').html_safe
+    instead.

app/views/projects/blob/_too_large.html.haml

-.file-content.code
-  .nothing-here-block
-    The file could not be displayed as it is too large, you can
-    #{link_to('view the raw file', namespace_project_raw_path(@project.namespace, @project, @id), target: '_blank', rel: 'noopener noreferrer')}
-    instead.