[backend] fix null pointer

[savacano28]

Proposed changes

Related issues

Checklist

• [ ] I consider the submitted work as finished
• [ ] I tested the code for its functionality
• [ ] I wrote test cases for the relevant uses case
• [ ] I added/update the relevant documentation (either on github or on notion)
• [ ] Where necessary I refactored code to improve the overall quality

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 26.83%. Comparing base (733e23e) to head (f218fd7).

Files	Patch %	Lines
...main/java/io/openbas/importer/V1_DataImporter.java	0.00%	8 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1134 +/- ## ============================================ + Coverage 26.55% 26.83% +0.27% - Complexity 1058 1062 +4 ============================================ Files 471 471 Lines 11192 11196 +4 Branches 567 569 +2 ============================================ + Hits 2972 3004 +32 + Misses 8136 8108 -28 Partials 84 84 ```

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