fix overlapping instances

Author: Poscat

src/Data/Aeson/Types/FromJSON.hs

@@ -1454,7 +1454,7 @@ instance (RecordFromJSON arity f, FieldNames f) => FromTaggedFlatObject' arity f
 instance FromTaggedFlatObject' arity U1 False where
     parseTaggedFlatObject' _ _ = Tagged (pure U1)
 
-instance PositionFromObject 1 arity f => FromTaggedFlatObject' arity f False where
+instance OVERLAPPABLE_ PositionFromObject 1 arity f => FromTaggedFlatObject' arity f False where
     parseTaggedFlatObject' (_ :* p) obj = Tagged (positionFromObject (Proxy :: Proxy 1) p obj)
 
 class KnownNat n => PositionFromObject n arity f where

src/Data/Aeson/Types/ToJSON.hs

@@ -954,7 +954,7 @@ instance RecordToPairs pairs enc arity f => TaggedFlatObject' pairs enc arity f
 instance Monoid pairs => TaggedFlatObject' enc pairs arity U1 False where
     taggedFlatObject' _ _ _ = Tagged mempty
 
-instance PositionToPairs 1 pairs enc arity f => TaggedFlatObject' enc pairs arity f False where
+instance OVERLAPPABLE_ PositionToPairs 1 pairs enc arity f => TaggedFlatObject' enc pairs arity f False where
     taggedFlatObject' opts targs a = Tagged $ positionToPairs (Proxy :: Proxy 1) opts targs a
 
 class KnownNat n => PositionToPairs n pairs enc arity f where