Hi
The error message displayed suggests that there may be a problem with the code of the OnAction() method of the 'XXX-Sales Invoices' page object in the extension.
I will list some suggestions
Check the code of the OnAction() method in Visual Studio for syntax errors or other problems. You can do this by opening the page object and navigating to the code of the OnAction() method.
Try rebuilding the extension by pressing Ctrl + Shift + B again to check for compilation errors or warnings in the code.
If the problem persists, try setting a breakpoint in the OnAction() method to see if you can locate where the error occurs.
Make sure that all the dependencies of the extension are set up and configured correctly, including the necessary libraries or packages.
If problems persist, you can try debugging the extension with the Visual Studio debugger to see if you can get more information on the cause of the error.
I hope this helps! Let me know if you have any further questions.
Daniele
