PdfDocument#getPage(int) returns null in case of broken page tree

Autoported commit.
Original commit hash: [5db36e2be]

Author: Snipx

itext/itext.io/itext/io/LogMessageConstant.cs

@@ -180,6 +180,8 @@ public sealed class LogMessageConstant {
 
         public const String OPENTYPE_GDEF_TABLE_ERROR = "OpenType GDEF table error: {0}";
 
+        public const String PAGE_TREE_IS_BROKEN_FAILED_TO_RETRIEVE_PAGE = "Page tree is broken. Failed to retrieve page number {0}. Null will be returned.";
+
         public const String PATH_KEY_IS_PRESENT_VERTICES_WILL_BE_IGNORED = "Path key is present. Vertices will be ignored";
 
         public const String PDF_OBJECT_FLUSHING_NOT_PERFORMED = "PdfObject flushing is not performed: PdfDocument is opened in append mode and the object is not marked as modified ( see PdfObject#setModified() ).";

itext/itext.kernel/itext/kernel/pdf/PdfDocument.cs

@@ -298,7 +298,11 @@ public virtual int GetNumberOfPdfObjects() {
 
         /// <summary>Gets the page by page number.</summary>
         /// <param name="pageNum">page number.</param>
-        /// <returns>page by page number.</returns>
+        /// <returns>
+        /// page by page number. may return
+        /// <see langword="null"/>
+        /// in case the page tree is broken
+        /// </returns>
         public virtual PdfPage GetPage(int pageNum) {
             CheckClosingStatus();
             return catalog.GetPageTree().GetPage(pageNum);

itext/itext.kernel/itext/kernel/pdf/PdfPagesTree.cs

@@ -118,10 +118,15 @@ public virtual PdfPage GetPage(int pageNum) {
             PdfPage pdfPage = pages[pageNum];
             if (pdfPage == null) {
                 LoadPage(pageNum);
-                pdfPage = new PdfPage(pageRefs[pageNum]);
-                int parentIndex = FindPageParent(pageNum);
-                PdfPages parentPages = parents[parentIndex];
-                pdfPage.parentPages = parentPages;
+                if (pageRefs[pageNum] != null) {
+                    int parentIndex = FindPageParent(pageNum);
+                    pdfPage = new PdfPage(pageRefs[pageNum]);
+                    pdfPage.parentPages = parents[parentIndex];
+                }
+                else {
+                    LogManager.GetLogger(GetType()).Error(MessageFormatUtil.Format(iText.IO.LogMessageConstant.PAGE_TREE_IS_BROKEN_FAILED_TO_RETRIEVE_PAGE
+                        , pageNum + 1));
+                }
                 pages[pageNum] = pdfPage;
             }
             return pdfPage;
@@ -357,7 +362,7 @@ private void LoadPage(int pageNum) {
                 }
                 PdfObject pageKids = page.Get(PdfName.Kids);
                 if (pageKids != null) {
-                    if (pageKids.GetObjectType() == PdfObject.ARRAY) {
+                    if (pageKids.IsArray()) {
                         findPdfPages = true;
                     }
                     else {

port-hash

@@ -1 +1 @@
-04d92262a715b272ebeba27d8cf01f6fcb793df6
+5db36e2be0d56e38c48b704886e0ceaf1149ff75