try fixing deviceserver crash for greg

js/deviceserver.js

@@ -81,7 +81,9 @@ wss.on('connection',function(ws) {
             if (cancel) {
                console.log('cancel')
                ws.send('cancel')
-               fs.close(file)
+               fs.close(file, (err) => {
+               	console.log("err at close file", err)
+               })
                }
             //
             // continue
@@ -100,7 +102,9 @@ wss.on('connection',function(ws) {
                      else {
                         console.log('done')
                         ws.send('done')
-                        fs.close(file)
+                        fs.close(file, (err) => {
+                        	console.log("err at close file", err)
+                        })
                         }
                      }
                   })