Error message on the widget client controller

[EliaquimS]

How do I put an error message on the widget client controller? Preventing the catalog item from being submitted.
Server Scripit: 
if (totalFTECalculation > 1) {
errorMessage('Message Here');
return;
}

Client Controller. 

[nv147]

Can you share your exact use case?

From what it sounds like, you may just want to create a catalog client script on the catalog item or items that would prevent submission.