update

src/drago.ts

@@ -26,7 +26,13 @@ export function handleTransfer(event: TransferEvent): void {
   entity.save()
   // update TokenOwner
   if (true) {
-    let ownerEntity= new TokenOwner(event.params.tokenId.toString())
+    let ownerEntity = TokenOwner.load(event.params.tokenId.toString())
+    if (ownerEntity != null) {
+      store.remove('TokenOwner', event.params.tokenId.toString())
+    } else {
+        ownerEntity = new TokenOwner(event.params.tokenId.toString())
+    }
+
     ownerEntity.owner = event.params.to
     ownerEntity.tokenId = event.params.tokenId
     ownerEntity.save()