Avoid looping through all the page tree if there is no destination page (spring-projects#3396)

* Avoid looping through all the page tree if there is no destination page

Fixes: spring-projects#3396

Auto-cherry-pick to 1.0.x

Signed-off-by: torakiki <[email protected]>

Author: torakiki

document-readers/pdf-reader/src/main/java/org/springframework/ai/reader/pdf/config/ParagraphManager.java

@@ -140,11 +140,13 @@ private int getPageNumber(PDOutlineItem current) throws IOException {
 			return -1;
 		}
 		PDPage currentPage = current.findDestinationPage(this.document);
-		PDPageTree pages = this.document.getDocumentCatalog().getPages();
-		for (int i = 0; i < pages.getCount(); i++) {
-			var page = pages.get(i);
-			if (page.equals(currentPage)) {
-				return i + 1;
+		if (currentPage != null) {
+			PDPageTree pages = this.document.getDocumentCatalog().getPages();
+			for (int i = 0; i < pages.getCount(); i++) {
+				var page = pages.get(i);
+				if (page.equals(currentPage)) {
+					return i + 1;
+				}
 			}
 		}
 		return -1;