Generics null check and ICollection added

null check for GetTypeWithGenericsInterfaceOf(typeof(IEnumerable<>)
and make ICollection behave the same as IEnumerable

Author: Wim Pool

src/ServiceStack.Text/Common/DeserializeSpecializedCollections.cs

@@ -52,9 +52,9 @@ public static ParseStringDelegate GetParseFn()
                 return ParseStringCollection<TSerializer>;
             }
 #endif
-            if (typeof(T) == typeof(IEnumerable))
+            if (typeof (T) == typeof (IEnumerable) || typeof(T) == typeof(ICollection))
             {
-                return GetEnumerableParseFn();
+                GetEnumerableParseFn();
             }
 
             return GetGenericEnumerableParseFn();
@@ -139,6 +139,7 @@ public static ParseStringDelegate GetEnumerableParseFn()
         public static ParseStringDelegate GetGenericEnumerableParseFn()
         {
             var enumerableInterface = typeof(T).GetTypeWithGenericInterfaceOf(typeof(IEnumerable<>));
+            if (enumerableInterface == null) return null; 
             var elementType = enumerableInterface.GenericTypeArguments()[0];
             var genericType = typeof(SpecializedEnumerableElements<,>).MakeGenericType(typeof(T), elementType);
             var fi = genericType.GetPublicStaticField("ConvertFn");
@@ -213,4 +214,4 @@ public static object ConvertFromCollection(object enumerable)
             return to;
         }
     }
-}
+}