Attempting to Export Registration Payment Reminder Grid Fails with NullReferenceException

[mcdude8675309]

Description

When trying to export the grid on the registration payment reminder page, we get a NullReferenceException. I have confirmed this happens in 15.1, 16.6 (our current version), and on the RockSolidChurchDemo site.

Actual Behavior

NullReferenceException in mscorlib
Message
Object reference not set to an instance of an object.

Stack Trace

at System.Object.GetType()
at Rock.Web.UI.Controls.Grid.GetDataSourceObjectType() in \Rock\Web\UI\Controls\Grid\Grid.cs:line 3006
at Rock.Web.UI.Controls.Grid.Actions_ExcelExportClick(Object sender, EventArgs e) in \Rock\Web\UI\Controls\Grid\Grid.cs:line 2413
at Rock.Web.UI.Controls.GridActions.lbExcelExport_Click(Object sender, EventArgs e) in \Rock\Web\UI\Controls\Grid\GridActions.cs:line 696
at System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e)
at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAs

Expected Behavior

The list of persons with outstanding transactions should be exported to Excel.

Steps to Reproduce

Assuming you have event registrations with outstanding payment balances...
Reminders

1. Go to an active registration instance with registrants having outstanding balances and click button "Send Payment Reminders"
2. Those with outstanding payments will be listed along with a preview of the reminder email that would be sent. Click the grid export button displayed at the upper right hand corner of the grid. Result is error screen with NullReferenceException.

Issue Confirmation

• Perform a search on the Github Issues to see if your bug or enhancement is already reported.
• Reproduced the problem on a fresh install or on the demo site.

Rock Version

15.1, 16.6

Client Culture Setting

en-US