Fix various crashes reported by UDC.

src/AddIns/BackendBindings/AspNet.Mvc/Project/Src/WebProjectOptions/WebProjectOptionsPanel.xaml.cs

@@ -176,7 +176,9 @@ namespace ICSharpCode.AspNet.Mvc
 		
 		void PortTextBox_KeyUp(object sender, KeyEventArgs e)
 		{
-			properties.DevelopmentServerPort = Int32.Parse(PortTextBox.Text);
+			int port;
+			if (int.TryParse(PortTextBox.Text, out port))
+				properties.DevelopmentServerPort = port;
 			properties.IISUrl = String.Format(@"{0}:{1}/", WebBehavior.LocalHost, PortTextBox.Text);
 		}
 	}

src/AddIns/Misc/SharpRefactoring/Project/Src/MethodExtractorBase.cs

@@ -137,6 +137,8 @@ namespace SharpRefactoring
 		
 		protected bool IsInCurrentSelection(Location location)
 		{
+			if (location.IsEmpty)
+				return false;
 			return IsInCurrentSelection(textEditor.Document.PositionToOffset(location.Line, location.Column));
 		}
 		

src/Main/Base/Project/Src/Services/ParserService/Doozer/ProjectContentRegistryDescriptor.cs

@@ -34,7 +34,12 @@ namespace ICSharpCode.SharpDevelop
 			// aren't used with project content registries, and this code
 			// will be removed in SD5.
 			#pragma warning disable 618
-			return codon.GetFailedAction(project) == ConditionFailedAction.Nothing;
+			try {
+				return codon.GetFailedAction(project) == ConditionFailedAction.Nothing;
+			} catch (ObjectDisposedException) {
+				// This method may be used on a background thread, so there's a chance that the project got disposed.
+				return false;
+			}
 		}
 		
 		public ProjectContentRegistryDescriptor(Codon codon)

src/Main/Base/Project/Src/Services/RefactoringService/ContextActions/EditorContext.cs

@@ -105,6 +105,8 @@ namespace ICSharpCode.SharpDevelop.Refactoring
 		
 		public ResolveResult ResolveExpression(Expression expression)
 		{
+			if (expression.EndLocation.IsEmpty)
+				return null;
 			ExpressionResult expr = GetExpressionAt(this.Editor, expression.EndLocation.Line, expression.EndLocation.Column);
 			return ResolveExpression(expr, this.Editor, expression.EndLocation.Line, expression.EndLocation.Column);
 		}

src/Main/ICSharpCode.SharpDevelop.Dom/Project/Src/XmlDoc.cs

@@ -68,8 +68,13 @@ namespace ICSharpCode.SharpDevelop.Dom
 		
 		public string GetDocumentation(string key)
 		{
-			if (xmlDescription == null)
+			if (xmlDescription == null) {
-				throw new ObjectDisposedException("XmlDoc");
+				//throw new ObjectDisposedException("XmlDoc");
+				// Sometimes SD accesses a project content after it is disposed.
+				// Not sure why, but we can avoid the crash by just returning null.
+				// SD5 fixes the issue by making IProjectContent immutable (no Dispose() method)
+				return null;
+			}
 			lock (xmlDescription) {
 				string result;
 				if (xmlDescription.TryGetValue(key, out result))