refactor: simplify null checks with optional chaining (#371)

This PR refactors conditional checks to use optional chaining, improving code readability and reducing boilerplate null checks.

- Logical operator can be refactored to optional chain: The original code used logical AND operators to guard property access (e.g., `if (levelEntry && levelEntry.rarity)` and `if (targetLink && targetLink.textContent.includes("Profile"))`), which can be verbose and error-prone. We replaced these with optional chaining (`if (levelEntry?.rarity)` and `if (targetLink?.textContent?.includes("Profile"))`) at the affected lines, ensuring safer and more concise null‐checks without altering runtime behavior.

> This Autofix was generated by AI. Please review the change before merging.

Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>

Author: deepsource-autofix[bot]

src/assets/js/script.js

@@ -1062,7 +1062,7 @@ function updateInventoryCounts(lvl) {
   // We use i <= lvl because currentLevel is the index reached
   for (let i = 0; i <= lvl; i++) {
     const levelEntry = LEVELS[i];
-    if (levelEntry && levelEntry.rarity) {
+    if (levelEntry?.rarity) {
       const r = levelEntry.rarity.toLowerCase();
       if (counts.hasOwnProperty(r)) {
         counts[r]++;
@@ -1198,7 +1198,7 @@ function initProfileTracker() {
     const targetLink = e.target.closest("a");
 
     // Only increment if the link text contains "Profile"
-    if (targetLink && targetLink.textContent.includes("Profile")) {
+    if (targetLink?.textContent?.includes("Profile")) {
       let currentCount = parseInt(
         localStorage.getItem("profile_view_count") || 0,
       );