From 2c2963608bf1c27b76bf766dca9080bd78fd363d Mon Sep 17 00:00:00 2001
From: Yusuke Nakamura <yusuke1994525@gmail.com>
Date: Tue, 24 Jun 2025 19:22:07 +0900
Subject: [PATCH] Add fallback codeblock render when coderay fails highlighting

CodeRay fails to render markdown codeblock with unknown lang tag
like that.

````
```unexistedlanguage
abcde
```
````

When coderay fails, render escaped code block without highlighting.
---
 app/helpers/application_helper.rb | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index bc428374d..d8ae91d30 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -16,6 +16,14 @@ class MarkdownRenderer < Redcarpet::Render::HTML
     def block_code(code, language)
       language ||= :ruby
       CodeRay.highlight(code, language)
+    rescue
+      <<~HTML
+        <div class="CodeRay">
+          <div class="code">
+            <pre>#{ERB::Util.html_escape(code)}</pre>
+          </div>
+        </div>
+      HTML
     end
   end