fix http://community.sharpdevelop.net/forums/t/15920.aspx - VB Parse - Unhandled Exception with embedded XML

src/Libraries/NRefactory/Project/Src/Lexer/VBNet/Lexer.cs

@@ -312,7 +312,10 @@ namespace ICSharpCode.NRefactory.Parser.VB
 						if (ch == '%' && ReaderPeek() == '>') {
 							int x = Col - 1;
 							int y = Line;
-							inXmlMode = true;
+							// in invalid code xmlModeStack might happen to be empty.
+							// do not set lexer to XML mode, if there was no valid XML before the inline VB code.
+							// fixes http://community.sharpdevelop.net/forums/t/15920.aspx
+							inXmlMode = xmlModeStack.Any();
 							ReaderRead();
 							return new Token(Tokens.XmlEndInlineVB, new Location(x, y), new Location(Col, Line));
 						}

src/Libraries/NRefactory/Test/Parser/SnippetParserTests.cs

@@ -26,5 +26,14 @@ namespace ICSharpCode.NRefactory.Tests
 			INode node = parser.Parse("Dim doc = <test><%= test %></test>");
 			Assert.IsTrue(parser.Errors.Count == 0);
 		}
+		
+		[Test]
+		public void InvalidXmlLiteral()
+		{
+			// ensure we don't crash on this invalid VB code
+			SnippetParser parser = new SnippetParser(SupportedLanguage.VBNet);
+			INode node = parser.Parse("<Cell StyleID=<%= print_title %>>");
+			Assert.IsTrue(parser.Errors.Count > 0);
+		}
 	}
 }