Merge branch 'tc-fix-snippets-notes-spec' into 'master'

Fix spec/features/snippets/notes_on_personal_snippets_spec.rb

Closes #31993

See merge request !11199

app/models/concerns/mentionable.rb

@@ -92,7 +92,7 @@ module Mentionable
   # Uses regex to quickly determine if mentionables might be referenced
   # Allows heavy processing to be skipped
   def matches_cross_reference_regex?
-    reference_pattern = if project.default_issues_tracker?
+    reference_pattern = if !project || project.default_issues_tracker?
                           ReferenceRegexes::DEFAULT_PATTERN
                         else
                           ReferenceRegexes::EXTERNAL_PATTERN