From 59ef730317d0b29567a16d15688ebf2b4bfc646c Mon Sep 17 00:00:00 2001
From: Tom Sydney Kerckhove <syd@cs-syd.eu>
Date: Thu, 20 May 2021 14:28:09 +0200
Subject: [PATCH] yesod-core: refactor the loop detector to not use Just
 wrapping

---
 yesod-core/src/Yesod/Core/Class/Breadcrumbs.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/yesod-core/src/Yesod/Core/Class/Breadcrumbs.hs b/yesod-core/src/Yesod/Core/Class/Breadcrumbs.hs
index 34069e7f..8bce0233 100644
--- a/yesod-core/src/Yesod/Core/Class/Breadcrumbs.hs
+++ b/yesod-core/src/Yesod/Core/Class/Breadcrumbs.hs
@@ -29,8 +29,8 @@ breadcrumbs = do
     go back Nothing = return back
     go back (Just this) = do
         (title, next) <- breadcrumb this
-        if next `elem` (map (Just . fst) back)
+        if this `elem` map fst back
         then
-          error $ "infinite recursion in breadcrumbs at" <> show title
+          error $ "yesod-core: infinite recursion in breadcrumbs at " <> show title
         else
           go ((this, title) : back) next