[IMP] hw_escpos: more fault tolerant printer detection

In some cases, the description fails (unknow printer, udev issues,...) and while
the printer works fine, the description fails.

addons/hw_escpos/controllers/main.py

@@ -77,10 +77,15 @@ class EscposDriver(Thread):
             printers = usb.core.find(find_all=True, idVendor=0x0519)
 
         for printer in printers:
+            try:
+                description = usb.util.get_string(printer, 256, printer.iManufacturer) + " " + usb.util.get_string(printer, 256, printer.iProduct)
+            except Exception as e:
+                _logger.error("Can not get printer description: %s" % (e.message or repr(e)))
+                description = 'Unknown printer'
             connected.append({
                 'vendor': printer.idVendor,
                 'product': printer.idProduct,
-                'name': usb.util.get_string(printer, 256, printer.iManufacturer) + " " + usb.util.get_string(printer, 256, printer.iProduct)
+                'name': description
             })
 
         return connected