Update FromJSON TickNumber instance to match ToJSON instance

src/swarm-engine/Swarm/Game/Tick.hs

@@ -17,11 +17,14 @@ import Swarm.Util.WindowedCounter (Offsettable (..))
 -- | A newtype representing a count of ticks (typically since the
 --   start of a game).
 newtype TickNumber = TickNumber {getTickNumber :: Int64}
-  deriving (Eq, Ord, Show, Read, Generic, FromJSON)
+  deriving (Eq, Ord, Show, Read, Generic)
 
 instance ToJSON TickNumber where
   toJSON = A.genericToJSON (A.defaultOptions {A.unwrapUnaryRecords = True})
 
+instance FromJSON TickNumber where
+  parseJSON = A.genericParseJSON (A.defaultOptions {A.unwrapUnaryRecords = True})
+
 -- | Add an offset to a 'TickNumber'.
 addTicks :: Int -> TickNumber -> TickNumber
 addTicks i (TickNumber n) = TickNumber $ n + fromIntegral i