Errol Spence is putting all his belts on the line Saturday night when he steps in the ring with Yordenis Ugas ... but it's the guy the undefeated boxing star wants next that'll be music to fan's ears -- Terence Crawford!! TMZ Sports spoke with the champ ahead of his unification bout against 27-4…

WBC Light Welterweight champ Terence Crawford -- who just came off a KO victory on Saturday -- was just hit with a 90 day jail sentence in connection with a disturbance at an Omaha body shop. Crawford was in front of an Omaha judge earlier Thursday on charges of property damage, trespassing, and…