fixed commit title when commit message is an empty string and ensured that link_to_gfm helper doesn't break on nil body

app/decorators/commit_decorator.rb

@@ -16,7 +16,7 @@ class CommitDecorator < ApplicationDecorator
   # In case this first line is longer than 80 characters, it is cut off
   # after 70 characters and ellipses (`&hellp;`) are appended.
   def title
-    return no_commit_message unless safe_message
+    return no_commit_message unless safe_message && !safe_message.strip.empty?
 
     title_end = safe_message.index(/\n/)
     if (!title_end && safe_message.length > 80) || (title_end && title_end > 80)

app/helpers/gitlab_markdown_helper.rb

@@ -11,6 +11,8 @@ module GitlabMarkdownHelper
   # explicitly produce the correct linking behavior (i.e.
   # "<a>outer text </a><a>gfm ref</a><a> more outer text</a>").
   def link_to_gfm(body, url, html_options = {})
+    return "" unless body && !body.strip.empty?
+    
     gfm_body = gfm(body, html_options)
 
     gfm_body.gsub!(%r{<a.*?>.*?</a>}m) do |match|