KR403 Status from Electron App

I'm currently working on an Electron app for a Kiosk using the KR403 printer.  We have received a requirement to display when the printer is unavailable, there's a paper jam, and paper is low/out.

 

Looking at some options, Browser Print seemed like the best bet.

 

After including it on the main page (for testing) with a script tag, I'm able to call BrowserPrint.getLocalDevices() and find the printer, including that it's connected via driver and so forth.  However, if I then call (following the demo code's checkPrinterStatus()) printer.sendThenRead("~HQES", ...) with that object, the response is an empty string.

 

Any thoughts as to where the disconnect is between the first call and the second?

 

Thanks!