Include type name in error message about missing field.

Author: drewnoakes

Dasher.Tests/DeserialiserTests.cs

@@ -283,7 +283,7 @@ public void ThrowsOnMissingField()
                 () => deserialiser.Deserialise(bytes));
 
             Assert.Equal(typeof(UserScore), ex.TargetType);
-            Assert.Equal("Missing required field \"score\".", ex.Message);
+            Assert.Equal("Missing required field \"score\" for type \"UserScore\".", ex.Message);
         }
 
         [Fact]

Dasher/DeserialiserEmitter.cs

@@ -329,9 +329,10 @@ public static Func<Unpacker, DasherContext, object> Build(Type type, UnexpectedF
             {
                 // If we got here then one or more values is missing.
                 ilg.MarkLabel(lblValuesMissing);
-                ilg.Emit(OpCodes.Ldstr, "Missing required field \"{0}\".");
+                ilg.Emit(OpCodes.Ldstr, "Missing required field \"{0}\" for type \"{1}\".");
                 ilg.Emit(OpCodes.Ldloc, paramName);
-                ilg.Emit(OpCodes.Call, typeof(string).GetMethod(nameof(string.Format), new[] {typeof(string), typeof(object)}));
+                ilg.Emit(OpCodes.Ldstr, type.Name);
+                ilg.Emit(OpCodes.Call, typeof(string).GetMethod(nameof(string.Format), new[] {typeof(string), typeof(object), typeof(object)}));
                 throwException();
             }
             ilg.MarkLabel(lblValuesOk);