handle astypedeclaration==null (#1625)

Author: Andrin Meier

Rubberduck.Parsing/Binding/IndexDefaultBinding.cs

@@ -132,6 +132,10 @@ with a parameter list that cannot accept any parameters and an <argument-list> t
                 IBoundExpression boundExpression = null;
                 var asTypeName = lExpression.ReferencedDeclaration.AsTypeName;
                 var asTypeDeclaration = lExpression.ReferencedDeclaration.AsTypeDeclaration;
+                if (asTypeDeclaration == null)
+                {
+                    return null;
+                }
                 boundExpression = ResolveDefaultMember(lExpression, asTypeName, asTypeDeclaration);
                 if (boundExpression != null)
                 {
@@ -169,8 +173,7 @@ private IBoundExpression ResolveDefaultMember(IBoundExpression lExpression, stri
                 The declared type of <l-expression> is a specific class, which has a public default Property 
                 Get, Property Let, function or subroutine, and one of the following is true:
             */
-            bool hasDefaultMember = asTypeDeclaration != null
-                && asTypeDeclaration.DeclarationType == DeclarationType.ClassModule
+            bool hasDefaultMember = asTypeDeclaration.DeclarationType == DeclarationType.ClassModule
                 && ((ClassModuleDeclaration)asTypeDeclaration).DefaultMember != null;
             if (hasDefaultMember)
             {