Keep a reference to an error outside of a try / except block

Question

Can someone please explain why the following code raises an error?

error = None

try:
    0 / 0
except ZeroDivisionError as error:
    pass

# Do some post-processing...

if error is not None:  # NameError: name 'error' is not defined
    raise error

The second-last line crashes with an error:

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-69-7ce6d086be88> in <module>()
      8 # Do some post-processing
      9 
---> 10 if error is not None:
     11     raise error

NameError: name 'error' is not defined

It seems that catching an error as a variable removes that variable from the stack after the try / except clause, but this seems very weird to me...