fix: No panic if filter condition on indexed field is empty

[islamaliev]

Relevant issue(s)

Resolves #2916

Description

Check if given filter condition is empty before proceeding with secondary index fetching.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.47%. Comparing base (defb37a) to head (81dcca6).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2929      +/-   ##
===========================================
- Coverage    79.51%   79.47%   -0.03%     
===========================================
  Files          325      325              
  Lines        24778    24781       +3     
===========================================
- Hits         19700    19694       -6     
- Misses        3669     3675       +6     
- Partials      1409     1412       +3     

Flag	Coverage Δ
all-tests	79.47% <100.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
internal/db/fetcher/indexer.go	85.71% <100.00%> (+2.83%)	⬆️
internal/db/fetcher/indexer_iterators.go	80.79% <100.00%> (+0.10%)	⬆️

... and 11 files with indirect coverage changes

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[fredcarle]

LGTM