Add Fuzzing

[AJGranowski]

Is your feature request related to a problem? Please describe.
OpenSSF recommends fuzzing, and adding fuzz testing to the project will increase the project's OpenSSF score.

Describe the solution you'd like
The recommended TypeScript tool for property-based fuzzing appears to be fast-check.

A solution should:

1. Add a fuzzing tool.
2. Identify critical areas in the code for fuzzing, such as user input or external data.
3. Add fuzzing coverage to those identified areas.
4. Open bug reports for any issues found by fuzzing.

Describe alternatives you've considered
fast-fuzz might work as an alternative. It doesn't seem like there's much consensus around fuzzing tools for TypeScript projects.

Additional context
See the wiki for getting started.

Tracking issue for:

• https://github.com/AJGranowski/reddit-expanded-community-filter-userscript/security/code-scanning/27