refactor: add return type

[tdeekens]

Summary

Description

Technical debt & future

[changeset-bot]

🦋 Changeset detected

Latest commit: 438ae24

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
@flopflip/launchdarkly-adapter	Patch
@flopflip/adapter-utilities	Patch
@flopflip/combine-adapters	Patch
@flopflip/cypress-plugin	Patch
@flopflip/graphql-adapter	Patch
@flopflip/http-adapter	Patch
@flopflip/localstorage-adapter	Patch
@flopflip/localstorage-cache	Patch
@flopflip/memory-adapter	Patch
@flopflip/react-broadcast	Patch
@flopflip/react-redux	Patch
@flopflip/react	Patch
@flopflip/sessionstorage-cache	Patch
@flopflip/splitio-adapter	Patch
@flopflip/test-utils	Patch
@flopflip/types	Patch

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 93.25%. Comparing base (35a43e4) to head (438ae24).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1869   +/-   ##
=======================================
  Coverage   93.25%   93.25%           
=======================================
  Files         109      109           
  Lines        1734     1734           
  Branches      254      260    +6     
=======================================
  Hits         1617     1617           
+ Misses        117      108    -9     
- Partials        0        9    +9     

Files	Coverage Δ
packages/launchdarkly-adapter/src/adapter/cache.ts	60.97% <0.00%> (ø)

... and 2 files with indirect coverage changes