Add cosplay related tags for other wikis

- Queries on *_(cosplay) tags will now also display the base tag.
- Also fixes an issue with list_of_* related wikis.
-- The request errors out if the list_of_* wiki doesn't actually exist.

app/logical/related_tag_query.rb

@@ -46,10 +46,29 @@ class RelatedTagQuery
   end
 
   def other_wiki_pages
-    return [] unless Tag.category_for(query) == Tag.categories.copyright
+    if Tag.category_for(query) == Tag.categories.copyright
+      copyright_other_wiki_pages
+    elsif Tag.category_for(query) == Tag.categories.general
+      general_other_wiki_pages
+    else
+      []
+    end
+  end
 
-    other_wikis = DText.parse_wiki_titles(wiki_page&.body&.to_s).grep(/\Alist_of_/i)
+  def copyright_other_wiki_pages
-    other_wikis = other_wikis.map { |name| WikiPage.titled(name).first }
+    list_of_wikis = DText.parse_wiki_titles(wiki_page&.body&.to_s).grep(/\Alist_of_/i)
+    map_tags_to_wikis(list_of_wikis)
+  end
+
+  def general_other_wiki_pages
+    match = query.match(/(.+?)_\(cosplay\)/)
+    return [] unless match
+    map_tags_to_wikis([match[1]])
+  end
+
+  def map_tags_to_wikis(other_tags)
+    other_wikis = other_tags.map { |name| WikiPage.titled(name).first }
+    other_wikis = other_wikis.reject { |wiki| wiki.nil? }
     other_wikis = other_wikis.select { |wiki| wiki.tags.present? }
     other_wikis
   end