I'm getting the following error after submission of a node that has a Rule acting upon it:

Now given this is core, I'm assuming I must have done something very wrong ... ?

Accepted answer

Yeah, so never mind. The issue arose because a page was deleted that had the URL-alias that the Rule was trying to redirect to. 
Maybe Core could have caught that the URL didn't exist, or maybe it's a Rules issue? IDK, but it's a logical failure.

Comments

Yeah, so never mind. The issue arose because a page was deleted that had the URL-alias that the Rule was trying to redirect to. 
Maybe Core could have caught that the URL didn't exist, or maybe it's a Rules issue? IDK, but it's a logical failure.

Please can you say more about the Rule? What does it do? Does it use any other Rule supporting modules? 

I presume if you disable the rule and create/save the node then you don't get the error.

The user fills a form on an Application node, that then flicks off emails, and responds with a  Thanks page.  Nothing too complex. 
Just that the deletion of the page providing the expected URL made the node module barf.