To me it doesn't look like you've started a conversation on itemEditor - hence the error message.
It seems unlikely that a long running conversation is starting in itemEditor without any method @Begin. You can check if a new conversation is acutally created on the debug page.
If you inject a stateless bean into a conversational bean then the stateless bean will exist for the lifespan of the conversational bean. I think something similaris happening here (but with a stateful bean that isn't long-running)?
My solution would be to add @Begin(join=true) to the @Create method of itemEditorBean. This will cause the itemEditor to join the existing conversation AND will be ended at the next @End annotation (in either bean).