fix #275 better exception message when using a custom contract resolver that does not extend ElasticResolver

Author: Mpdreamz

src/Nest.Tests.Unit/Nest.Tests.Unit.csproj

@@ -215,6 +215,7 @@
     <Compile Include="Search\SearchType\ScriptFieldTests.cs" />
     <Compile Include="Internals\Serialize\SerializeTests.cs" />
     <Compile Include="Search\Sort\SortTests.cs" />
+    <Compile Include="Settings\UsePrettyResponseTests.cs" />
     <Compile Include="Test.Designer.cs">
       <DependentUpon>Test.settings</DependentUpon>
       <AutoGen>True</AutoGen>

src/Nest/Resolvers/Converters/IndexNameMarkerConverter.cs

@@ -22,13 +22,14 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
 				writer.WriteNull();
 				return;
 			}
+
 			var settings = serializer.ContractResolver as ElasticResolver;
 			if (settings != null && settings.ConnectionSettings != null)
 			{
 				var typeName = marker.Resolve(settings.ConnectionSettings);
 				writer.WriteValue(typeName);
 			}
-			else throw new Exception("Could not find connection settings on the json contract resolver");
+			else throw new Exception("If you use a custom contract resolver be sure to subclass from ElasticResolver");
 		}
 
 		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

src/Nest/Resolvers/Converters/TypeNameMarkerConverter.cs

@@ -28,7 +28,7 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
 				var typeName = marker.Resolve(settings.ConnectionSettings);
 				writer.WriteValue(typeName);
 			}
-			else throw new Exception("Could not find connection settings on the json contract resolver");
+			else throw new Exception("If you use a custom contract resolver be sure to subclass from ElasticResolver");
 		}
 
 		public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)