SEAB-6452: fix null error

[hyunnaye]

Description
This PR fixes the null error found during sprint demo.

Review Instructions
Same as #492

Issue
https://ucsc-cgl.atlassian.net/browse/SEAB-6452

Security
If there are any concerns that require extra attention from the security team, highlight them here.

Please make sure that you've checked the following before submitting your pull request. Thanks!

• Check that you pass the basic style checks and unit tests by running mvn clean install in the project that you have modified (until https://ucsc-cgl.atlassian.net/browse/SEAB-5300 adds multi-module support properly)
• Ensure that the PR targets the correct branch. Check the milestone or fix version of the ticket.
• If you are changing dependencies, check with dependabot to ensure you are not introducing new high/critical vulnerabilities
• If this PR is for a user-facing feature, create and link a documentation ticket for this feature (usually in the same milestone as the linked issue). Style points if you create a documentation PR directly and link that instead.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.13%. Comparing base (141e9ca) to head (75b96ba).

Additional details and impacted files

@@            Coverage Diff             @@
##             develop     #496   +/-   ##
==========================================
  Coverage      45.13%   45.13%           
  Complexity       305      305           
==========================================
  Files             47       47           
  Lines           2663     2663           
  Branches         205      205           
==========================================
  Hits            1202     1202           
  Misses          1368     1368           
  Partials          93       93           

Flag	Coverage Δ
metricsaggregator	36.91% <ø> (ø)
toolbackup	23.16% <ø> (ø)
tooltester	17.31% <ø> (ø)
topicgenerator	19.67% <ø> (ø)

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[coverbeck]

Was here, going to wait for response to other feedback first; please re-request review then.

[sonarcloud]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarCloud