diff --git a/Gemfile b/Gemfile
index 4504ecde..ca8a8f5c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -53,6 +53,9 @@ gem "letter_opener", :group => :development
 # For parallel API calls.
 gem "parallel", "~> 1.13.0"
 
+# For debugging.
+gem 'web-console', '~> 2.2', '>= 2.2.1'
+
 # TODO: Rails requests the latest version of these dependencies, but they
 # require Ruby 2.5 or higher, so we have to request lower ones instead!
 # (loofah is slightly trickier: it requires a recent nokogiri, but recent
diff --git a/Gemfile.lock b/Gemfile.lock
index 23cbc0c7..b72b0835 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -48,6 +48,8 @@ GEM
       babel-source (>= 4.0, < 6)
       execjs (~> 2.0)
     bcrypt (3.1.19)
+    binding_of_caller (1.0.0)
+      debug_inspector (>= 0.0.1)
     builder (3.2.4)
     capistrano (2.15.5)
       highline
@@ -75,6 +77,7 @@ GEM
     concurrent-ruby (1.2.2)
     connection_pool (2.2.5)
     crass (1.0.6)
+    debug_inspector (1.1.0)
     devise (4.9.2)
       bcrypt (~> 3.0)
       orm_adapter (~> 0.1)
@@ -226,6 +229,11 @@ GEM
       execjs (>= 0.3.0, < 3)
     warden (1.2.7)
       rack (>= 1.0)
+    web-console (2.3.0)
+      activemodel (>= 4.0)
+      binding_of_caller (>= 0.7.2)
+      railties (>= 4.0)
+      sprockets-rails (>= 2.0, < 4.0)
     will_paginate (3.0.7)
 
 PLATFORMS
@@ -262,6 +270,7 @@ DEPENDENCIES
   sanitize (~> 2.0.3)
   sass-rails (~> 5.0, >= 5.0.7)
   uglifier (~> 4.2)
+  web-console (~> 2.2, >= 2.2.1)
   will_paginate (~> 3.0.pre2)
 
 RUBY VERSION
diff --git a/config/application.rb b/config/application.rb
index 57c8e73d..71d1217b 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -32,6 +32,8 @@ module OpenneoImpressItems
     config.assets.initialize_on_precompile = false
 
     config.middleware.insert_after ActionDispatch::Flash, Rack::Attack
+
+    config.active_record.raise_in_transactional_callbacks = true
   end
 end
 
diff --git a/vendor/cache/binding_of_caller-1.0.0.gem b/vendor/cache/binding_of_caller-1.0.0.gem
new file mode 100644
index 00000000..81be9b1d
Binary files /dev/null and b/vendor/cache/binding_of_caller-1.0.0.gem differ
diff --git a/vendor/cache/debug_inspector-1.1.0.gem b/vendor/cache/debug_inspector-1.1.0.gem
new file mode 100644
index 00000000..c16993e8
Binary files /dev/null and b/vendor/cache/debug_inspector-1.1.0.gem differ
diff --git a/vendor/cache/web-console-2.3.0.gem b/vendor/cache/web-console-2.3.0.gem
new file mode 100644
index 00000000..d0d61cc2
Binary files /dev/null and b/vendor/cache/web-console-2.3.0.gem differ