fix: additional real bug fixes

Author: Saurabh Kumar Bajpai

frontend/js/app.js

@@ -907,7 +907,7 @@ class BookRenderer {
                         <div class="handwritten-note" style="margin-bottom: 0.8rem; font-style: italic; color: #5d4037;">${safeVibe}</div>
                         ${bookData.moods && bookData.moods.length > 0 ? `
                         <div class="book-mood-tags" style="margin-bottom: 0.8rem; display: flex; flex-wrap: wrap; gap: 4px;">
-                            ${bookData.moods.map(m => `<span style="font-size: 0.6rem; background: rgba(0,0,0,0.1); padding: 2px 6px; border-radius: 10px;"><i class="fa-solid ${this.getMoodIcon(m)}"></i> ${m}</span>`).join('')}
+                            ${bookData.(moods ?? []).map(m => `<span style="font-size: 0.6rem; background: rgba(0,0,0,0.1); padding: 2px 6px; border-radius: 10px;"><i class="fa-solid ${this.getMoodIcon(m)}"></i> ${m}</span>`).join('')}
                         </div>
                         ` : ''}
                     </div>

frontend/js/book-preview.js

@@ -107,7 +107,7 @@ const BookPreview = (() => {
         el.setAttribute('aria-modal', 'true');
         el.setAttribute('aria-label', 'Book preview');
 
-        el.innerHTML = `
+        el.textContent = `
             <div class="preview-modal-inner">
                 <div class="preview-modal-header">
                     <div class="preview-modal-title-wrap">

frontend/js/library-3d.js

@@ -1070,7 +1070,7 @@ class BookshelfRenderer3D {
         const localLibrary = this.getLibraryState();
         let books = [...(localLibrary[shelfType] || [])];
 
-        books = books.map(b => {
+        books = (books ?? []).map(b => {
             if (b.volumeInfo) {
                 return {
                     id: b.id,