ActionView::Template::Error in Projects::CommitController#diff_files

Sentry error: https://new-sentry.gitlab.net/organizations/gitlab/issues/518061

TypeError: no implicit conversion of Hash into String
  from lib/gitlab/dependency_linker/base_linker.rb:34:in `match?'
  from lib/gitlab/dependency_linker/base_linker.rb:34:in `external_url'
  from lib/gitlab/dependency_linker/package_json_linker.rb:27:in `block in link_packages_at_key'
  from lib/gitlab/dependency_linker/package_json_linker.rb:26:in `each'
  from lib/gitlab/dependency_linker/package_json_linker.rb:26:in `link_packages_at_key'
  from lib/gitlab/dependency_linker/package_json_linker.rb:18:in `link_packages'
  from lib/gitlab/dependency_linker/package_json_linker.rb:14:in `link_dependencies'
  from lib/gitlab/dependency_linker/base_linker.rb:28:in `link'
  from lib/gitlab/dependency_linker/json_linker.rb:9:in `link'
  from lib/gitlab/dependency_linker/base_linker.rb:17:in `link'