espi_update_fpga.py throws exception at end of execution

[jburks]

After a seemingly successful update, espi_update throws an exception related to accessing a closed port:

Erasing sector 0x019000...Waited 11 loops
Writing page 0x019000
Writing page 0x019100
Writing page 0x019200
Writing page 0x019300
Writing page 0x019400
Writing page 0x019500
Writing page 0x019600
Traceback (most recent call last):
  File "C:\Dev\Python\vera_espi_test.py", line 140, in <module>
    ser.write(b'\xf0')
  File "C:\Users\joe_b\AppData\Roaming\Python\Python310\site-packages\serial\serialwin32.py", line 306, in write
    raise PortNotOpenError()
serial.serialutil.PortNotOpenError: Attempting to use a port that is not open