Improved DbEntityValidationException message

DbEntityValidationException.cs

 public partial class MyContext
 {
     // Adapted from https://blogs.infosupport.com/improving-dbentityvalidationexception/
     public override Task<int> SaveChangesAsync()
     {
         try
         {
             return base.SaveChangesAsync();
         }
         catch (DbEntityValidationException exception)
         {
            var errorMessage = new StringBuilder();
            foreach (var validationError in exception.EntityValidationErrors)
            {
                errorMessage.AppendLine($"* {validationError.Entry.Entity.GetType().FullName} ({validationError.Entry.State})");
                foreach (var error in validationError.ValidationErrors)
                {
                    errorMessage.AppendLine($"    - {error.ErrorMessage}");
                }
            }
            var entityCount = exception.EntityValidationErrors.Count();
            var entity = entityCount == 1 ? "entity" : "entities";
            throw new DbEntityValidationException($"Validation failed for {entityCount} {entity}. See below for more details." + Environment.NewLine + errorMessage, exception.EntityValidationErrors);
         }
    }
}