Avoid NullReferenceException when pasting text.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@4267 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/NewLineFinder.cs

@@ -51,6 +51,8 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// </summary>
 		public static string NormalizeNewLines(string input, string newLine)
 		{
+			if (input == null)
+				return null;
 			Debug.Assert(IsNewLine(newLine));
 			SimpleSegment ds = NextNewLine(input, 0);
 			if (ds == SimpleSegment.Invalid) // text does not contain any new lines

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Editing/EditingCommandHandler.cs

@@ -344,6 +344,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 				string newLine = NewLineFinder.GetNewLineFromDocument(textArea.Document, textArea.Caret.Line);
 				string text = NewLineFinder.NormalizeNewLines(Clipboard.GetText(), newLine);
 				
+				if (!string.IsNullOrEmpty(text)) {
 					bool fullLine = textArea.Options.CutCopyWholeLine && Clipboard.ContainsData(LineSelectedType);
 					if (fullLine) {
 						DocumentLine currentLine = textArea.Document.GetLineByNumber(textArea.Caret.Line);
@@ -351,6 +352,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 					} else {
 						textArea.ReplaceSelectionWithText(text);
 					}
+				}
 				textArea.Caret.BringCaretToView();
 				args.Handled = true;
 			}