Error 500 viewing a commit: ActionView::Template::Error: undefined method `name' for nil:NilClass

https://sentry.gitlap.com/gitlab/gitlabcom/issues/115379/

NoMethodError: undefined method `name' for nil:NilClass
  app/views/projects/diffs/_stats.html.haml:27:in `block in _app_views_projects_diffs__stats_html_haml___1591822185001983342_70121047945920'
    %strong.diff-changed-file-name= diff_file.blob.name
  lib/gitlab/git/diff_collection.rb:40:in `each'
    @array.each(&block)
  lib/gitlab/git/diff_collection.rb:40:in `each'
    @array.each(&block)
  app/views/projects/diffs/_stats.html.haml:22:in `_app_views_projects_diffs__stats_html_haml___1591822185001983342_70121047945920'
    - diff_files.each do |diff_file|
  app/views/projects/diffs/_diffs.html.haml:22:in `_app_views_projects_diffs__diffs_html_haml__1774216531917193688_70121052258400'
    = render 'projects/diffs/stats', diff_files: diff_files
...
(184 additional frame(s) were not displayed)

ActionView::Template::Error: undefined method `name' for nil:NilClass

ActionView::Template::Error: undefined method `name' for nil:NilClass