Simple update of record during the Create event.

Simple table of books with prices.

Create a plugin to run in the Create message.

Plugin is run Synchronous and in pre-validation

Expected Result :  take the price of the book and multiply it by 10% and store it in the GSTPrice field  of the same record

namespace Library
    {
    public class CalcGSTPrice : IPlugin
        {
        public void Execute(IServiceProvider serviceProvider)
            {
            //Obtain the execution context from the service provider.
           Microsoft.Xrm.Sdk.IPluginExecutionContext context = (Microsoft.Xrm.Sdk.IPluginExecutionContext)
           serviceProvider.GetService(typeof(Microsoft.Xrm.Sdk.IPluginExecutionContext));
            // create a trace log so you can see where in the code it breaks
            ITracingService tracingService = (ITracingService)serviceProvider.GetService(typeof(ITracingService));
            // create access to service
            IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
            IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);
            tracingService.Trace("have reached execute event in plugin.");

            Entity newRecord = (Entity)context.InputParameters["Target"];
            if (newRecord != null)
                {
                if (newRecord.Contains("new_price"))
                    {
                    // Get price of book
                    Decimal price = newRecord.GetAttributeValue<Money>("new_price").Value;
                    // increase price of book by 10%
                    price = Decimal.Multiply(price, (Decimal)1.1);
                    // create new attribute and set value to new price of book
                    newRecord.Attributes.Add("new_gstprice", new Money(price));
                    tracingService.Trace("Update of new_gstprice has completed");
                    }
                }

            tracingService.Trace("Last line of plugin execute method reached");
            }
        }
    }

Actual Result: Exception is thrown but trace shows All lines of plug in were executed.

If I run the error log in debug all lines execute without an exception.

No new record is created.

Trace log shows exception message.

I'm unable to determine the cause of the issue as all lines of code in the plugin run without issue.

Any suggestions?

Erick