Rewrite unknown property handling in FileSerializer

Configuration/SystemConfig.cs

@@ -6,7 +6,7 @@
 namespace TweetDuck.Configuration{
     sealed class SystemConfig{
         private static readonly FileSerializer<SystemConfig> Serializer = new FileSerializer<SystemConfig>{
-            OnReadUnknownProperty = (obj, property, value) => false
+            // HandleUnknownProperties = (obj, data) => {}
         };
 
         public static readonly bool IsHardwareAccelerationSupported = File.Exists(Path.Combine(Program.ProgramPath, "libEGL.dll")) &&

Configuration/UserConfig.cs

@@ -10,9 +10,10 @@
 
 namespace TweetDuck.Configuration{
     sealed class UserConfig{
-        private static readonly FileSerializer<UserConfig> Serializer = new FileSerializer<UserConfig>{
-            OnReadUnknownProperty = (obj, property, value) => false
-        };
+        private static readonly FileSerializer<UserConfig> Serializer = new FileSerializer<UserConfig>{ HandleUnknownProperties = HandleUnknownProperties };
+
+        private static void HandleUnknownProperties(UserConfig obj, Dictionary<string, string> data){
+        }
 
         static UserConfig(){
             Serializer.RegisterTypeConverter(typeof(WindowState), WindowState.Converter);

Data/Serialization/FileSerializer.cs

@@ -12,8 +12,8 @@ sealed class FileSerializer<T>{
 
         private static readonly ITypeConverter BasicSerializerObj = new BasicTypeConverter();
         
-        public delegate bool OnReadUnknownPropertyHandler(T obj, string property, string value);
-        public OnReadUnknownPropertyHandler OnReadUnknownProperty { get; set; }
+        public delegate void HandleUnknownPropertiesHandler(T obj, Dictionary<string, string> data);
+        public HandleUnknownPropertiesHandler HandleUnknownProperties { get; set; }
         
         private readonly Dictionary<string, PropertyInfo> props;
         private readonly Dictionary<Type, ITypeConverter> converters;
@@ -51,6 +51,8 @@ public void Write(string file, T obj){
         }
 
         public void Read(string file, T obj){
+            Dictionary<string, string> unknownProperties = new Dictionary<string, string>(4);
+
             using(StreamReader reader = new StreamReader(new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.Read))){
                 if (reader.Peek() <= 1){
                     throw new FormatException("Input appears to be a binary file.");
@@ -78,11 +80,19 @@ public void Read(string file, T obj){
                             throw new SerializationException($"Invalid file format, cannot convert value: {value} (property: {property})");
                         }
                     }
-                    else if (!(OnReadUnknownProperty?.Invoke(obj, property, value) ?? false)){
-                        throw new SerializationException($"Invalid file format, unknown property: {property}+");
+                    else{
+                        unknownProperties[property] = value;
                     }
                 }
             }
+
+            if (unknownProperties.Count > 0){
+                HandleUnknownProperties?.Invoke(obj, unknownProperties);
+
+                if (unknownProperties.Count > 0){
+                    throw new SerializationException($"Invalid file format, unknown properties: {string.Join(", ", unknownProperties.Keys)}+");
+                }
+            }
         }
 
         private class BasicTypeConverter : ITypeConverter{