Fixed client showing wrong spool price if overridden to 0

Resolves #431

client/src/pages/spools/list.tsx

@@ -56,7 +56,7 @@ function collapseSpool(element: ISpool): ISpoolCollapsed {
   } else {
     filament_name = element.filament.name ?? element.filament.id.toString();
   }
-  if (!element.price) {
+  if (element.price === undefined) {
     element.price = element.filament.price;
   }
   return {

client/src/pages/spools/show.tsx

@@ -32,7 +32,7 @@ export const SpoolShow: React.FC<IResourceComponentsProps> = () => {
 
   const spoolPrice = (item: ISpool) => {
     let spoolPrice = "";
-    if (!item.price) {
+    if (item.price === undefined) {
       spoolPrice = `${item.filament.price}`;
       return spoolPrice;
     }