Add exception details to GraphQL request logs

We rescue StandardError in the controller so we need to manually add the
exception to the ActiveSupport instrumentation payload so that it gets
logged

app/controllers/graphql_controller.rb

@@ -50,6 +50,8 @@ class GraphqlController < ApplicationController
   end
 
   rescue_from StandardError do |exception|
+    @exception_object = exception
+
     log_exception(exception)
 
     if Rails.env.test? || Rails.env.development?
@@ -197,7 +199,9 @@ class GraphqlController < ApplicationController
 
     # Merging to :metadata will ensure these are logged as top level keys
     payload[:metadata] ||= {}
-    payload[:metadata].merge!(graphql: logs)
+    payload[:metadata][:graphql] = logs
+
+    payload[:exception_object] = @exception_object if @exception_object
   end
 
   def logs

spec/controllers/graphql_controller_spec.rb

@@ -262,5 +262,16 @@ RSpec.describe GraphqlController do
       expect(controller).to have_received(:append_info_to_payload)
       expect(log_payload.dig(:metadata, :graphql)).to match_array(expected_logs)
     end
+
+    it 'appends the exception in case of errors' do
+      exception = StandardError.new('boom')
+
+      expect(controller).to receive(:execute).and_raise(exception)
+
+      post :execute, params: { _json: graphql_queries }
+
+      expect(controller).to have_received(:append_info_to_payload)
+      expect(log_payload.dig(:exception_object)).to eq(exception)
+    end
   end
 end