Fix "Unhandled exception when installing packed addin with incorrect .addin file" (http://community.sharpdevelop.net/forums/t/11807.aspx)

src/Main/Core/Project/Src/AddInTree/AddIn/AddIn.cs

@@ -267,22 +267,26 @@ namespace ICSharpCode.Core
 		
 		public static AddIn Load(TextReader textReader, string hintPath)
 		{
-			AddIn addIn = new AddIn();
-			using (XmlTextReader reader = new XmlTextReader(textReader)) {
-				while (reader.Read()){
-					if (reader.IsStartElement()) {
-						switch (reader.LocalName) {
-							case "AddIn":
-								addIn.properties = Properties.ReadFromAttributes(reader);
-								SetupAddIn(reader, addIn, hintPath);
-								break;
-							default:
-								throw new AddInLoadException("Unknown add-in file.");
+			try {
+				AddIn addIn = new AddIn();
+				using (XmlTextReader reader = new XmlTextReader(textReader)) {
+					while (reader.Read()){
+						if (reader.IsStartElement()) {
+							switch (reader.LocalName) {
+								case "AddIn":
+									addIn.properties = Properties.ReadFromAttributes(reader);
+									SetupAddIn(reader, addIn, hintPath);
+									break;
+								default:
+									throw new AddInLoadException("Unknown add-in file.");
+							}
 						}
 					}
 				}
+				return addIn;
+			} catch (XmlException ex) {
+				throw new AddInLoadException(ex.Message, ex);
 			}
-			return addIn;
 		}
 		
 		public static AddIn Load(string fileName)