ExportFormatter: Add book description and check for empty book and chapter descriptions in markdown export

Author: czemu

app/Entities/Tools/ExportFormatter.php

@@ -315,7 +315,11 @@ public function pageToMarkdown(Page $page): string
     public function chapterToMarkdown(Chapter $chapter): string
     {
         $text = '# ' . $chapter->name . "\n\n";
-        $text .= $chapter->description . "\n\n";
+
+        if (!empty($chapter->description)) {
+            $text .= $chapter->description . "\n\n";
+        }
+
         foreach ($chapter->pages as $page) {
             $text .= $this->pageToMarkdown($page) . "\n\n";
         }
@@ -330,6 +334,11 @@ public function bookToMarkdown(Book $book): string
     {
         $bookTree = (new BookContents($book))->getTree(false, true);
         $text = '# ' . $book->name . "\n\n";
+        
+        if (!empty($book->description)) {
+            $text .= $book->description . "\n\n";
+        }
+
         foreach ($bookTree as $bookChild) {
             if ($bookChild instanceof Chapter) {
                 $text .= $this->chapterToMarkdown($bookChild) . "\n\n";