Bugfix in M365 Dumper Module

[0x534a]

🗣 Description

This PR fixes a bug in the M365 dumper module. The bug produces an KeyError exception which leads to a crash of the application.

💭 Motivation and context

The exception is thrown in the function dump_exo_mailbox of the m365_datadumper.py. The complete stack trace can be found below.

Traceback (most recent call last):
  File "venv/goose/bin/goosey", line 11, in <module>
    load_entry_point('goosey==1.1.0', 'console_scripts', 'goosey')()
  File "venv/goose/lib/python3.8/site-packages/goosey/main.py", line 89, in main
    honkmain(args)
  File "venv/goose/lib/python3.8/site-packages/goosey/honk.py", line 278, in main
    asyncio.run(run(args, config, auth, auth_un_pw))
  File "/usr/lib/python3.8/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "venv/goose/lib/python3.8/site-packages/goosey/honk.py", line 145, in run
    await asyncio.gather(*tasks)
  File "venv/goose/lib/python3.8/site-packages/goosey/m365_datadumper.py", line 278, in dump_exo_mailbox
    del result['@odata.context']
KeyError: '@odata.context'

As seen in the stack trace the key @odata.context is not part of the result dictionary. Thus, I suggest to check whether the key exists beforehand.

🧪 Testing

This PR was tested manually against a Microsoft 365 development tenant (E5 license).

✅ Pre-approval checklist

• [x] This PR has an informative and human-readable title.
• [x] Changes are limited to a single goal - eschew scope creep!
• [x] All future TODOs are captured in issues, which are referenced in code comments.
• [ ] All relevant type-of-change labels have been added.
• [x] I have read the CONTRIBUTING document.
• [ ] These code changes follow cisagov code standards.
• [ ] All relevant repo and/or project documentation has been updated to reflect the changes in this PR.
• [ ] Tests have been added and/or modified to cover the changes in this PR.
• [ ] All new and existing tests pass.

✅ Pre-merge checklist

• [ ] Revert dependencies to default branches.
• [ ] Finalize version.

✅ Post-merge checklist

• [ ] Create a release.

[victoriawallace-cisa]

Thanks! We tested it as well and it works well. We'll go ahead and incorporate the pull request. Thank you!