fix: add thread safety primitives to internal shard list

[braindigitalis]

fix adds shared lock to shards list so that accessing the shards list doesnt risk crashing the lib. Has never crashed in production for me but still the issue exists and should be patched.

Code change checklist

• I have ensured that all methods and functions are fully documented using doxygen style comments.
• My code follows the coding style guide.
• I tested that my change works before raising the PR.
• I have ensured that I did not break any existing API calls.
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[Mishura4]

Merperson 👀