SettingsManager: ignore missing types & add error event

Pilz.Configuration/SettingsManager.cs

@@ -2,6 +2,8 @@
 using System.Collections.Generic;
 using System.IO;
 using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+using ErrorEventArgs = Newtonsoft.Json.Serialization.ErrorEventArgs;
 
 namespace Pilz.Configuration
 {
@@ -10,6 +12,7 @@ namespace Pilz.Configuration
         public event EventHandler AutoSavingSettings;
         public event EventHandler SavingSettings;
         public event EventHandler SavedSettings;
+        public event EventHandler<ErrorEventArgs> OnSerializationError;
 
         protected ISettings defaultInstance = null;
         protected bool enableAutoSave = false;
@@ -119,8 +122,21 @@ namespace Pilz.Configuration
             return new JsonSerializerSettings()
             {
                 Formatting = Formatting.Indented,
-                TypeNameHandling = TypeNameHandling.Auto
+                TypeNameHandling = TypeNameHandling.Auto,
+                Error = JsonSerializer_OnError,
             };
         }
+
+        protected virtual void JsonSerializer_OnError(object sender, ErrorEventArgs e)
+        {
+            const string errorResolvingType = "Error resolving type specified in JSON";
+
+            // Invoke event
+            OnSerializationError?.Invoke(sender, e);
+
+            // Handle ourself
+            if (!e.ErrorContext.Handled && e.ErrorContext.Error is JsonSerializationException serializationException && serializationException.Message.StartsWith(errorResolvingType))
+                e.ErrorContext.Handled = true;
+        }
     }
 }