Fixed possible null reference exception.

ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngineBase.cs

@@ -415,9 +415,9 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 				wrapper.Append (';');
 		}
 
-		protected CompilationUnit ParseStub(string continuation, bool appendSemicolon = true, string afterContinuation = null)
+		protected CompilationUnit ParseStub (string continuation, bool appendSemicolon = true, string afterContinuation = null)
 		{
-			var mt = GetMemberTextToCaret();
+			var mt = GetMemberTextToCaret ();
 			if (mt == null) {
 				return null;
 			}
@@ -429,33 +429,35 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 			var wrapper = new StringBuilder ();
 			bool wrapInClass = memberLocation != new TextLocation (1, 1);
 			if (wrapInClass) {
-				var nodeAtLocation = Unit.GetNodeAt(memberLocation, n => n is TypeDeclaration || n is NamespaceDeclaration);
-				foreach (var n in nodeAtLocation.AncestorsAndSelf) {
-					if (memberLocation == n.StartLocation) {
-						continue;
-					}
-					if (n is TypeDeclaration) {
-						var t = (TypeDeclaration)n;
-						switch (t.ClassType) {
+				var nodeAtLocation = Unit.GetNodeAt (memberLocation, n => n is TypeDeclaration || n is NamespaceDeclaration);
+				if (nodeAtLocation != null) {
+					foreach (var n in nodeAtLocation.AncestorsAndSelf) {
+						if (memberLocation == n.StartLocation) {
+							continue;
+						}
+						if (n is TypeDeclaration) {
+							var t = (TypeDeclaration)n;
+							switch (t.ClassType) {
 							case ClassType.Class:
-								wrapper.Append("class");
+								wrapper.Append ("class");
 								break;
 							case ClassType.Struct:
-								wrapper.Append("struct");
+								wrapper.Append ("struct");
 								break;
 							case ClassType.Interface:
-								wrapper.Append("interface");
+								wrapper.Append ("interface");
 								break;
 							case ClassType.Enum:
-								wrapper.Append("enum");
+								wrapper.Append ("enum");
 								break;
+							}
+							wrapper.Append (" " + t.Name + " {");
+							wrapper.AppendLine ();
+							closingBrackets++;
+							generatedLines++;
+						} else {
+							Console.WriteLine (n);
 						}
-						wrapper.Append(" " + t.Name + " {");
-						wrapper.AppendLine();
-						closingBrackets++;
-						generatedLines++;
-					} else {
-						Console.WriteLine(n);
 					}
 				}
 			}