[Serialization] More useful throw when missing parameterless ctor

sources/core/Stride.Core.Yaml.Tests/Serialization/SerializationTests.cs

@@ -816,6 +816,25 @@ public void DeserializeWithRepeatedSubObjects()
             Assert.Equal(22, family.Mother.Age);
         }
 
+        [Fact]
+        public void ThrowWithoutEmptyCtor()
+        {
+            try
+            {
+                SerializeThenDeserialize(new ClassWithNonEmptyCtor(default));
+                Assert.Fail("An exception should have been thrown given that the class cannot be instanced because of the missing empty constructor ");
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<DefaultObjectFactory.InstanceCreationException>(ex.InnerException);
+            }
+        }
+
+        class ClassWithNonEmptyCtor 
+        {
+            public ClassWithNonEmptyCtor(bool parameter) { }
+        }
+
 
         [Fact]
         public void DeserializeEmptyDocument()

sources/core/Stride.Core.Yaml/Serialization/DefaultObjectFactory.cs

@@ -99,13 +99,14 @@ public static Type GetDefaultImplementation(Type type)
             return type;
         }
 
+        /// <inheritdoc/>
         public object Create(Type type)
         {
             type = GetDefaultImplementation(type);
 
-            // We can't instantiate primitive or arrays
+            // We can't instantiate primitives or arrays
             if (PrimitiveDescriptor.IsPrimitive(type) || type.IsArray)
-                return null;
+                throw new InstanceCreationException($"Failed to create instance of type '{type}', wrong factory.");
 
             if (type.GetConstructor(EmptyTypes) != null || type.IsValueType)
             {
@@ -119,11 +120,12 @@ public object Create(Type type)
                 }
             }
 
-            return null;
+            throw new InstanceCreationException($"Failed to create instance of type '{type}', type does not implement a parameterless constructor.");
         }
 
         public class InstanceCreationException : Exception
         {
+            public InstanceCreationException(string message) : base(message) { }
             public InstanceCreationException(string message, Exception innerException) : base(message, innerException) { }
         }
     }

sources/core/Stride.Core.Yaml/Serialization/IObjectFactory.cs

@@ -1,4 +1,4 @@
-// Copyright (c) 2015 SharpYaml - Alexandre Mutel
+// Copyright (c) 2015 SharpYaml - Alexandre Mutel
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -56,8 +56,8 @@ namespace Stride.Core.Yaml.Serialization
     public interface IObjectFactory
     {
         /// <summary>
-        /// Creates an instance of the specified type. Returns null if instance cannot be created.
+        /// Creates an instance of the specified type. Throws with an appropriate exception if the type cannot be created.
         /// </summary>
         object Create(Type type);
     }
-}
+}