From 1fa4f1eb81920ccd87caca5d70de301747db046a Mon Sep 17 00:00:00 2001
From: slush <info@bitcoin.cz>
Date: Sat, 31 Aug 2013 23:45:53 +0200
Subject: [PATCH] Test if USB device is presented

---
 cmd.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/cmd.py b/cmd.py
index 246f77b916..cdfe2d81c4 100755
--- a/cmd.py
+++ b/cmd.py
@@ -44,7 +44,10 @@ def get_transport(transport_string, path):
         from bitkeylib.transport_hid import HidTransport
 
         if path == '':
-            path = list_usb()[0]
+            try:
+                path = list_usb()[0]
+            except IndexError:
+                raise Exception("No Trezor found on USB")
 
         return HidTransport(path)