i2c transaction fails when readline() times out

[alvarop]

In line 196, when an error occurs, it tries to return an error code
rbytes = int(result[1])
This is ok if the error was in an i2c transaction. If the silta board hangs for whatever reason (which technically shouldn't happen, but I still don't have a solid I2C library) the ERR is never printed, so we get an index out of bounds error on result[]