IOS get_network_instances fails 'KeyError' when deleting item from interfaces

[cromulon-actual]

Description of Issue/Question

Issue with ios driver for getting VRFs. On Cat3850 running Fuji 16.9.x code, when performing the get_network_instances line 3431 (deleting items from interfaces from network instances nested dict) returns an error: line 3431, in get_network_instances del instances["default"]["interfaces"]["interface"][item] KeyError: 'LI18/2'

Suggestion is to set conditional statement:

 if item in instances["default"]["interfaces"]["interface"]:
     del instances["default"]["interfaces"]["interface"][item]

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Did you follow the steps from https://github.com/napalm-automation/napalm#faq

(Place an x between the square brackets where applicable)

• [] Yes
• No

Setup

napalm version

(Paste verbatim output from pip freeze | grep napalm between quotes below)

napalm==3.2.0
nornir-napalm==0.1.1

Network operating system version

(Paste verbatim output from show version - or equivalent - between quotes below)

Switch Ports Model              SW Version        SW Image              Mode   
------ ----- -----              ----------        ----------            ----   
*    1 62    WS-C3850-12X48U    16.9.4            CAT3K_CAA-UNIVERSALK9 INSTALL
     2 62    WS-C3850-12X48U    16.9.4            CAT3K_CAA-UNIVERSALK9 INSTALL
     3 62    WS-C3850-12X48U    16.9.4            CAT3K_CAA-UNIVERSALK9 INSTALL

Steps to Reproduce the Issue

Error Traceback

(Paste the complete traceback of the exception between quotes below)

2021-03-03 09:36:49,204 - nornir.core.task -    ERROR -      start() - Host 'SANITIZED': task 'napalm_get' failed with traceback:
Traceback (most recent call last):
  File "/Users/SANITIZED/Documents/Private/python_projects/Network_Automation/lib/python3.9/site-packages/nornir/core/task.py", line 98, in start
    r = self.task(self, **self.params)
  File "/Users/SANITIZED/Documents/Private/python_projects/Network_Automation/lib/python3.9/site-packages/nornir_napalm/plugins/tasks/napalm_get.py", line 44, in napalm_get
    result[g] = method(**options)
  File "/Users/SANITIZED/Documents/Private/python_projects/Network_Automation/lib/python3.9/site-packages/napalm/ios/ios.py", line 3431, in get_network_instances
    del instances["default"]["interfaces"]["interface"][item]
KeyError: 'LI18/2'

[DavidVentura]

what is this issue waiting for? I can make the PR if that's what's missing

[mirceaulinic]

Yep, a PR would do it @DavidVentura, cheers!