Disable webpacker stylesheet errors in production

Webpacker has a nasty habit of not compiling css files for components and then causing an error in production when they are missing.
rails/webpacker#2342
rails/webpacker#2059 (comment)
This adds an override which causes no errors in production but still allows us to leave the stylesheet_pack_tag for when it is needed.

app/helpers/webpacker_overrides.rb

@@ -0,0 +1,24 @@
+# Webpacker has a nasty habit of not compiling css files for components and then
+# causing an error in production when they are missing. This file silences
+# the errors in production as well, making for a consistent experience across
+# environments
+
+# app/helpers/webpacker_overrides.rb
+module WebpackerOverrides
+  private
+    def rescued_pack_tags
+      @rescued_pack_tags ||= {}
+    end
+
+    def sources_from_manifest_entries(names, type:)
+      names.map do |name|
+        unless (type == :stylesheet) && rescued_pack_tags[name]
+          current_webpacker_instance.manifest.lookup!(name, type: type)
+        end
+      rescue
+        raise unless type == :stylesheet
+        rescued_pack_tags[name] = true
+        nil
+      end.flatten.select(&:present?)
+    end
+end