Handle error when searching for files

src/freedombone-keydrive

 fi
 
 no_of_usb_shares=$(ls -afq $FRAGMENTS_DIR/keyshare.asc.* | wc -l)
-no_of_usb_shares=$((no_of_usb_shares - 2))
+if [ ! "$?" = "0" ]; then
+    no_of_usb_shares=0
+else
+    no_of_usb_shares=$((no_of_usb_shares - 2))
+fi
 if [[ ${no_of_usb_shares} > 0 ]]; then
   echo "A key fragment already exists on the drive for the user $MY_USERNAME"
   umount $USB_MOUNT
 fi
 
 no_of_local_shares=$(ls -afq $LOCAL_FRAGMENTS_DIR/keyshare.asc.* | wc -l)
-no_of_local_shares=$((no_of_shares - 2))
+if [ ! "$?" = "0" ]; then
+    no_of_local_shares=0
+else
+    no_of_local_shares=$((no_of_local_shares - 2))
+fi
 if [[ ${no_of_local_shares} < 3 ]]; then
     freedombone-splitkey -u $MY_USERNAME
     no_of_local_shares=$(ls -afq $LOCAL_FRAGMENTS_DIR/keyshare.asc.* | wc -l)
+    if [ ! "$?" = "0" ]; then
+        no_of_local_shares=0
+    else
+        no_of_local_shares=$((no_of_local_shares - 2))
+    fi
     no_of_local_shares=$((no_of_shares - 2))
 fi