Fix rewriting issue references with group milestones

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/gitlab/gfm/reference_rewriter.rb b/lib/gitlab/gfm/reference_rewriter.rb
index b984492d369..455814a9159 100644
--- a/lib/gitlab/gfm/reference_rewriter.rb
+++ b/lib/gitlab/gfm/reference_rewriter.rb
@@ -29,6 +29,8 @@ module Gitlab
     #  http://gitlab.com/some/link/#1234, and code `puts #1234`'
     #
     class ReferenceRewriter
+      RewriteError = Class.new(StandardError)
+
       def initialize(text, source_project, current_user)
         @text = text
         @source_project = source_project
@@ -61,6 +63,10 @@ module Gitlab
         cross_reference = build_cross_reference(referable, target_project)
         return reference if reference == cross_reference
 
+        if cross_reference.nil?
+          raise RewriteError, "Unspecified reference detected for #{referable.class.name}"
+        end
+
         new_text = before + cross_reference + after
         substitution_valid?(new_text) ? cross_reference : reference
       end