Fixed parsing of switch statements.

ICSharpCode.NRefactory.CSharp/Parser/CSharpParser.cs

@@ -1662,8 +1662,10 @@ namespace ICSharpCode.NRefactory.CSharp
 					result.AddChild (new CSharpTokenNode (Convert (location [1]), 1), SwitchStatement.Roles.RPar);
 				if (location != null && location.Count > 2)
 					result.AddChild (new CSharpTokenNode (Convert (location [2]), 1), SwitchStatement.Roles.LBrace);
+				if (switchStatement.Sections != null) {
 					foreach (var section in switchStatement.Sections) {
 						var newSection = new SwitchSection ();
+						if (section.Labels != null) {
 							foreach (var caseLabel in section.Labels) {
 								var newLabel = new CaseLabel ();
 								if (caseLabel.Label != null) {
@@ -1678,6 +1680,7 @@ namespace ICSharpCode.NRefactory.CSharp
 								}
 								newSection.AddChild (newLabel, SwitchSection.CaseLabelRole);
 							}
+						}
 						
 						var blockStatement = section.Block;
 						var bodyBlock = new BlockStatement ();
@@ -1690,6 +1693,7 @@ namespace ICSharpCode.NRefactory.CSharp
 						}
 						result.AddChild (newSection, SwitchStatement.SwitchSectionRole);
 					}
+				}
 				
 				if (location != null && location.Count > 3) {
 					result.AddChild (new CSharpTokenNode (Convert (location [3]), 1), SwitchStatement.Roles.RBrace);