Apply suggestions from code review

Author: tim-barry

engine/collection/pusher/engine.go

@@ -146,7 +146,7 @@ func (e *Engine) processOutboundMessages(ctx context.Context) error {
 // Because the pusher engine does not accept inputs from the network,
 // always drop any messages and return an error.
 func (e *Engine) Process(channel channels.Channel, originID flow.Identifier, message any) error {
-	return fmt.Errorf("pusher engine should only receive local messages on the same node")
+	return fmt.Errorf("pusher engine should only receive local messages on the same node: got message %T on channel %v from origin %v", message, channel, originID)
 }
 
 // SubmitCollectionGuarantee adds a collection guarantee to the engine's queue

engine/collection/pusher/engine_test.go

@@ -97,8 +97,6 @@ func (suite *Suite) TestSubmitCollectionGuarantee() {
 		Run(func(_ mock.Arguments) { close(done) }).Return(nil).Once()
 
 	suite.engine.SubmitCollectionGuarantee(guarantee)
-	// TODO signature?
-	//suite.Require().Nil(err)
 
 	unittest.RequireCloseBefore(suite.T(), done, time.Second, "message not sent")