Merge branch 'dm-empty-tree-readme' into 'master'

Don't blow up when a tree readme is empty and consequently has no rich viewer

Closes #32396

See merge request !11459

Conflicts:
	app/views/projects/tree/_readme.html.haml

app/views/projects/tree/_readme.html.haml

+<<<<<<< HEAD
 %article.file-holder.readme-holder
   .js-file-title.file-title
     = blob_icon readme.mode, readme.name
@@ -6,3 +7,14 @@
         = readme.name
   .file-content.wiki
     = markup(readme.name, readme.data)
+=======
+- if readme.rich_viewer
+  %article.file-holder.readme-holder
+    .js-file-title.file-title
+      = blob_icon readme.mode, readme.name
+      = link_to namespace_project_blob_path(@project.namespace, @project, tree_join(@ref, readme.path)) do
+        %strong
+          = readme.name
+
+    = render 'projects/blob/viewer', viewer: readme.rich_viewer, viewer_url: namespace_project_blob_path(@project.namespace, @project, tree_join(@ref, readme.path), viewer: :rich, format: :json)
+>>>>>>> a30aa41... Merge branch 'dm-empty-tree-readme' into 'master'