Add missing JSDoc @returns

[dpvc]

This PR adds missing JSDoc @returns lines for some recently added methods, fixing lint complaints.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.66%. Comparing base (27c47f3) to head (c1e0c1c).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1371   +/-   ##
========================================
  Coverage    86.66%   86.66%           
========================================
  Files          338      338           
  Lines        84384    84384           
  Branches      4779     4779           
========================================
  Hits         73131    73131           
+ Misses       11253    11230   -23     
- Partials         0       23   +23     

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