If we throw exception from approveIt, then Approval workflow terminated and not report any error to user.
This cause user to think that it approved as request removed from workflow activities.

Steps to Produce.

As ApproveIt validation only possible to implement in Model class, for producing issue, used change event and make sure that exception thrown from same block of code.
Environment setup

1. Login to system tenant and import 2pack Loading file... . This 2pack add approval workflow supports into purchase order.

2. Download and extract Loading file... . This zip has plugin adding event handler which throw exception when purchase order description is empty while approving perchase order. either install binary added in plugin folder using osgi console or add source code in eclipse.

Test Step

1. Login with GardenUser in Garden world tenant.

2. Create purchase order keeping description blank.

3. Complete PO. This should show suspended message.

4. Login as GardenAdmin and open workflow activities.

5. it should show Activities to approve purchase order. Select it.

6. On Answer, Select Yes and then click on ok button.
   Expected result: It should show error message “Must provide approval comments in description" and workflow activity should show there
   Actual result : No error reported and workflow activities disappear from approver’s queue. Workflow process is terminated

I tested the fix and creating PR for same.