fix

lib/pages/supply.dart

@@ -38,7 +38,7 @@ class _SupplyPageState extends State<SupplyPage> {
     availableVariants =
         widget.onlyVariants ?? widget.item.variants.keys.toList();
 
-    variant = widget.item.variants.keys.first;
+    variant = availableVariants.first;
 
     _selectedOrigin = widget.forceOrigin ?? "";
     _priceController = TextEditingController(text: widget.forcePrice ?? "");
@@ -310,6 +310,17 @@ class SupplyForm {
     );
   }
 
+  Map<String, dynamic> json() {
+    return {
+      "item": itemID,
+      "variant": variant,
+      "price": price,
+      "origin": origin,
+      "location": location,
+      "note": note
+    };
+  }
+
   SupplyForm({
     required this.itemID,
     required this.variant,