fix segmentation fault error

[kushalmalani]

Description

Describe the purpose of this pull request.

Fixes nil pointer segmentation fault error on deployment variable modify with no deployments in workspace

🎟 Issue(s)

Related #1592

🧪 Functional Testing

List the functional testing steps to confirm this feature or fix.

📸 Screenshots

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📋 Checklist

• [ ] Rebased from the main (or release if patching) branch (before testing)
• [ ] Ran make test before taking out of draft
• [ ] Ran make lint before taking out of draft
• [ ] Added/updated applicable tests
• [ ] Tested against Astro-API (if necessary).
• [ ] Tested against Houston-API and Astronomer (if necessary).
• [ ] Communicated to/tagged owners of respective clients potentially impacted by these changes.
• [ ] Updated any related documentation

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.55%. Comparing base (847b57d) to head (933f7ea).

:exclamation: Current head 933f7ea differs from pull request most recent head 224f2f7. Consider uploading reports for the commit 224f2f7 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1596 +/- ## ======================================= Coverage 86.55% 86.55% ======================================= Files 114 114 Lines 15935 15935 ======================================= Hits 13792 13792 Misses 1288 1288 Partials 855 855 ```

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