fix: Resolved panic triggered by using an empty string as a template value

[dadrus]

Related issue(s)

fixes #2272

Checklist

• I agree to follow this project's Code of Conduct.
• I have read, and I am following this repository's Contributing Guidelines.
• I have read the Security Policy.
• I have referenced an issue describing the bug/feature request.
• I have added tests that prove the correctness of my implementation.

Description

Fixes the referenced bug

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.49%. Comparing base (0700616) to head (e35862c).
Report is 1 commits behind head on release.

Additional details and impacted files

@@             Coverage Diff             @@
##           release    #2274      +/-   ##
===========================================
- Coverage    89.49%   89.49%   -0.01%     
===========================================
  Files          271      271              
  Lines        11502    11496       -6     
===========================================
- Hits         10294    10288       -6     
  Misses         967      967              
  Partials       241      241              

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