Make sure that we don't crash if the ILVariable original value is null or the index is out of range.

Debugger/Debugger.Core/MetaData/DebugMethodInfo.cs

@@ -471,7 +471,8 @@ namespace Debugger.MetaData
 				corVal = context.CorILFrame.GetLocalVariable((uint)varIndex);
 			} catch (COMException e) {
 				if ((uint)e.ErrorCode == 0x80131304) throw new GetValueException("Unavailable in optimized code");
-				throw;
+				// show the message in case of bad index
+				throw new GetValueException(e.Message);
 			}
 			return new Value(context.AppDomain, corVal);
 		}

Debugger/ILSpy.Debugger/Models/TreeModel/ExpressionNode.cs

@@ -163,12 +163,12 @@ namespace ILSpy.Debugger.Models.TreeModel
 				IEnumerable<ILVariable> list;
 				if (ILAstBuilder.MemberLocalVariables.TryGetValue(token, out list)) {
 					var variable = list.FirstOrDefault(v => v.Name == targetName);
-					if (variable != null) {
+					if (variable != null && variable.OriginalVariable != null) {
 						if (expression is MemberReferenceExpression) {
 							var memberExpression = (MemberReferenceExpression)expression;
-							memberExpression.Target.AddAnnotation(new int[] { variable.OriginalVariable.Index });
+							memberExpression.Target.AddAnnotation(new [] { variable.OriginalVariable.Index });
 						} else {
-							expression.AddAnnotation(new int[] { variable.OriginalVariable.Index });
+							expression.AddAnnotation(new [] { variable.OriginalVariable.Index });
 						}
 					}
 				}