Bugfix from PDFsharp forum.

Author: TH-Soft

src/PdfSharp/Drawing.Layout/XTextFormatter.cs

@@ -194,6 +194,7 @@ void CreateBlocks()
                     blockLength = 0;
                     _blocks.Add(new Block(BlockType.LineBreak));
                 }
+                // The non-breaking space is whitespace, so we treat it like non-whitespace.
                 else if (ch != Chars.NonBreakableSpace && char.IsWhiteSpace(ch))
                 {
                     if (inNonWhiteSpace)

src/PdfSharp/Pdf/PdfDictionary.cs

@@ -818,7 +818,9 @@ public PdfItem GetValue(string key, VCF options)
                 PdfArray array;
                 PdfReference iref;
                 PdfItem value = this[key];
-                if (value == null)
+                if (value == null ||
+                    value is PdfNull ||
+                    value is PdfReference && ((PdfReference)value).Value is PdfNullObject)
                 {
                     if (options != VCF.None)
                     {