It is a naturalistic fallacy if someone concludes from there is something to something ought to be. If you reverse that order you have someone concluding from something ought to be to there is something. This should be a quite obvious fallacy, but you see it surprisingly often - often in debates about the existence of god ("It would be terrible if there would be no god as there would be no reason to act morally. Therefore god exists" the last bit is often just implied)
Is there a name for this fallacy? Or does it fall within the scope of the naturalistic fallacy?