fix(item): format negative resistances (#3696)

Co-authored-by: Helias <stefanoborzi32@gmail.com>

Author: sogladev

libs/features/item/src/item-template/item-preview.service.spec.ts

@@ -813,6 +813,11 @@ describe('ItemPreviewService', () => {
       template: { holy_res: 1, arcane_res: 1 },
       output: `<br>+1 Holy Resistance<br>+1 Arcane Resistance`,
     },
+    {
+      name: 'Negative resistance',
+      template: { holy_res: -5 },
+      output: `<br>-5 Holy Resistance`,
+    },
     {
       name: 'Gem Enchantment - success',
       template: { entry: 100 },

libs/features/item/src/item-template/item-preview.service.ts

@@ -1022,8 +1022,9 @@ export class ItemPreviewService {
     // magic resistances
     resistanceFields.forEach((rowName, idx) => {
       const resField = itemTemplate[rowName + '_res'];
-      if (rowName != null && resField != null && resField !== 0) {
-        magicRsistances += `<br>+${resField} ${ITEM_CONSTANTS.resistances[idx]}`;
+      if (rowName != null && resField != null && Number(resField) !== 0) {
+        const num = Number(resField);
+        magicRsistances += `<br>${num > 0 ? '+' + num : String(num)} ${ITEM_CONSTANTS.resistances[idx]}`;
       }
     });