Return early from markdown and gfm when text is empty

app/helpers/gitlab_markdown_helper.rb

@@ -45,6 +45,8 @@ module GitlabMarkdownHelper
   end
 
   def markdown(text, context = {})
+    return unless text.present?
+
     context.merge!(
       path:         @path,
       project:      @project,
@@ -59,6 +61,8 @@ module GitlabMarkdownHelper
   # TODO (rspeicher): Remove all usages of this helper and just call `markdown`
   # with a custom pipeline depending on the content being rendered
   def gfm(text, options = {})
+    return unless text.present?
+
     options.merge!(
       path:         @path,
       project:      @project,

app/views/events/_event_issue.atom.haml

 %div{xmlns: "http://www.w3.org/1999/xhtml"}
-  - if issue.description.present?
   = markdown(issue.description, xhtml: true, reference_only_path: false, project: issue.project)

app/views/events/_event_merge_request.atom.haml

 %div{xmlns: "http://www.w3.org/1999/xhtml"}
-  - if merge_request.description.present?
   = markdown(merge_request.description, xhtml: true, reference_only_path: false, project: merge_request.project)