fix: server deletion lockup

[mihaicm93]

Fixes client lockup "can't access property 'values'" and "can't convert undefined to BigInt" on server deletion or server leave by adding safe returns on object deletion

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Closes: stoatchat/for-web#574
stoatchat/for-web#641

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Supersedes: stoatchat/for-web#803

[mihaicm93]

> stoat.js@7.3.7 fmt:check /home/runner/work/javascript-client-sdk/javascript-client-sdk
> prettier --check 'src/**/*.{js,jsx,ts,tsx}'

Checking formatting...
[warn] src/events/EventClient.ts
[warn] Code style issues found in the above file. Run Prettier with --write to fix.
 ELIFECYCLE  Command failed with exit code 1.
Error: Process completed with exit code 1.

I did not even touch the file where Lint fails