Unpin unnecessary patched gem for rambulance for this reason:

#1631 (comment)

Author: yasulab

Gemfile

@@ -19,12 +19,7 @@ gem 'sass-rails', '>= 5'
 # https://gihyo.jp/article/2024/01/ruby3.3-bundled-gems
 gem 'csv'
 
-
-# For handling error by Rambulance: https://github.com/yuki24/rambulance
-# FIXME: Using patch gem due to NameError: uninitialized constant ApplicationHelper
-# https://github.com/coderdojo-japan/coderdojo.jp/pull/1631#issuecomment-2424826474
-gem 'rambulance', git: 'https://github.com/yasslab/rambulance'
-
+gem 'rambulance'         # Error handling pages: https://github.com/yuki24/rambulance
 gem 'airbrake'           # Error Monitoring by Airbrake: https://github.com/airbrake/airbrake
 gem 'rack-host-redirect' # Enable redirection
 gem 'secure_headers'     # Enable SSL and CORS

Gemfile.lock

@@ -1,12 +1,3 @@
-GIT
-  remote: https://github.com/yasslab/rambulance
-  revision: f422d939d2fb415a920b1816b6026da522e96e5e
-  specs:
-    rambulance (3.3.0)
-      actionpack
-      activesupport
-      railties
-
 GEM
   remote: https://rubygems.org/
   specs:
@@ -394,6 +385,10 @@ GEM
       zeitwerk (~> 2.6)
     rainbow (3.1.1)
     rake (13.2.1)
+    rambulance (3.3.0)
+      actionpack
+      activesupport
+      railties
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
@@ -585,7 +580,7 @@ DEPENDENCIES
   rails-controller-testing
   rails-html-sanitizer
   rake
-  rambulance!
+  rambulance
   rinku
   rspec-rails (~> 6.1.1)
   rspec-retry