Fix output metadata timer fallback

lib/gruf/interceptors/instrumentation/output_metadata_timer.rb

@@ -28,7 +28,7 @@ class OutputMetadataTimer < ::Gruf::Interceptors::ServerInterceptor
         # Handle the instrumented response. Note: this will only instrument timings of _successful_ responses.
         #
         def call(&block)
-          return unless active_call.respond_to?(:output_metadata)
+          return yield unless active_call.respond_to?(:output_metadata)
 
           result = Gruf::Interceptors::Timer.time(&block)
           output_metadata.update(metadata_key => result.elapsed.to_s)

spec/gruf/interceptors/instrumentation/output_metadata_timer_spec.rb

@@ -39,5 +39,22 @@
         expect(request.active_call.output_metadata[:foo]).not_to be_nil
       end
     end
+
+    context 'when the active call does not support output metadata' do
+      let(:active_call) { double(:active_call) }
+      let(:request) { build(:controller_request, method_key: :get_thing, active_call: active_call) }
+
+      it 'still executes the request' do
+        executed = false
+
+        result = interceptor.call do
+          executed = true
+          :result
+        end
+
+        expect(executed).to be(true)
+        expect(result).to eq(:result)
+      end
+    end
   end
 end