How to unassociate an output port

[Helveg]

During my code for registration as a parallel output there's sometimes errors, and I'd like to fully revert in the except clause, note here how the 2nd attempt gets stuck on a new error left over from the previous registration:

>>> p.ParallelCon(s3(0), 2)
NEURON: Can't associate gid 2. PreSyn already associated with gid 1.
 near line 0
 ^
        ParallelContext[0].cell(2, ...)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/robin/git/bsb/libs/nrn-patch/patch/interpreter.py", line 189, in ParallelCon
    self.parallel.cell(gid, nc)
  File "/home/robin/git/bsb/libs/nrn-patch/patch/interpreter.py", line 386, in cell
    transform(self).cell(gid, transform(nc))
RuntimeError: hocobj_call error: hoc_execerror: Can't associate gid 2. PreSyn already associated with gid 1.
>>> p.ParallelCon(s3(0.000001), 2)
NEURON: gid=2 already exists on this process as an output port
 near line 0
 ^
        ParallelContext[0].set_gid2node(2, 0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/robin/git/bsb/libs/nrn-patch/patch/interpreter.py", line 188, in ParallelCon
    self.parallel.set_gid2node(gid, self.parallel.id())
  File "/home/robin/git/bsb/libs/nrn-patch/patch/interpreter.py", line 397, in set_gid2node
    return transform(self).set_gid2node(gid, id)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RuntimeError: hocobj_call error: hoc_execerror: gid=2 already exists on this process as an output port

I think these are the relevant steps taken:

                self.parallel.set_gid2node(gid, self.parallel.id())
                self.parallel.cell(gid, nc)
                if output:
                    self.parallel.outputcell(gid)

How can I undo these operations so that it's safe for the user to try my ParallelCon again?

[nrnhines]

At the moment, from the interpreter, it is only possible to clear all the gids with https://nrn.readthedocs.io/en/latest/progref/modelspec/programmatic/network/parcon.html#ParallelContext.gid_clear

However, looking at the implementation of set_gid2node and noting that the error message occurs before any internal structures are changed, you are safe to continue after the exception. I.e. the gid has not been registered and the next parallel.cell method has not been executed.