Always use symbols for type on LabelsHelper#link_to_label

app/helpers/labels_helper.rb

@@ -46,7 +46,7 @@ module LabelsHelper
     end
   end
 
-  def label_filter_path(subject, label, type: issue)
+  def label_filter_path(subject, label, type: :issue)
     case subject
     when Group
       send("#{type.to_s.pluralize}_group_path",

app/views/projects/merge_requests/_merge_request.html.haml

@@ -62,7 +62,7 @@
     - if merge_request.labels.any?
        
       - merge_request.labels.each do |label|
-        = link_to_label(label, subject: merge_request.project, type: 'merge_request')
+        = link_to_label(label, subject: merge_request.project, type: :merge_request)
     - if merge_request.tasks?
        
       %span.task-status