Add default handlers to HttpExceptionHandler

Introduce static methods for creating HttpExceptionHandler instances for specific exceptions. Define default message factory and handlers for common HTTP status codes, including a generic handler that returns a JSON response for internal server errors.

DigitalData.Core.Exceptions.Middleware/HttpExceptionHandler.cs

@@ -7,6 +7,7 @@ namespace DigitalData.Core.Exceptions.Middleware;
 
 public record HttpExceptionHandler(Type ExceptionType, Func<HttpContext, Exception, ILogger?, Task> HandleExceptionAsync)
 {
+    #region Alternative generator methods
     public static HttpExceptionHandler Create<TException>(Func<HttpContext, Exception, ILogger?, Task> HandleExceptionAsync) where TException : Exception
         => new HttpExceptionHandler(typeof(TException), HandleExceptionAsync);
 
@@ -20,10 +21,22 @@ public record HttpExceptionHandler(Type ExceptionType, Func<HttpContext, Excepti
             await context.Response.WriteAsync(JsonSerializer.Serialize(new { message }));
         }
     );
+    #endregion
 
+    #region Default handlers
     public static readonly Func<Exception, string> DefaultMessageFactory = ex => ex.Message;
 
     public static readonly HttpExceptionHandler DefaultBadRequest = Create<BadRequestException>(HttpStatusCode.BadRequest, DefaultMessageFactory);
 
     public static readonly HttpExceptionHandler DefaultNotFound = Create<NotFoundException>(HttpStatusCode.NotFound, DefaultMessageFactory);
+
+    public static readonly HttpExceptionHandler Default = Create<Exception>(
+        async (context, ex, logger) =>
+        {
+            context.Response.ContentType = "application/json";
+            context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
+            var message = "An unexpected error occurred.";
+            await context.Response.WriteAsync(JsonSerializer.Serialize(new { message }));
+        });
+    #endregion
 };