Ensure we always generate a valid URL

Defaults to the homepage, if for some reason the canonical URL is nil

app/helpers/events_helper.rb

@@ -188,7 +188,7 @@ module EventsHelper
   end
 
   def event_wiki_page_target_url(event)
-    project_wiki_url(event.project, event.target.canonical_slug)
+    project_wiki_url(event.project, event.target&.canonical_slug || Wiki::HOMEPAGE)
   end
 
   def event_note_title_html(event)

changelogs/unreleased/ajk-safe-wiki-event-url.yml

+---
+title: Ensure we always generate a valid wiki event URL
+merge_request: 34191
+author:
+type: fixed