ESLint: Set "no-unnecessary-condition" rule to error

[regexowl]

This adds "no-unnecessary-condition" and sets the output to error. This should help us eliminate superfluous conditional chaining and uncover potentially faulty conditions.

Docs: https://typescript-eslint.io/rules/no-unnecessary-condition/

[regexowl]

My IDE is clever, I'm usually not (especially when I copy over a part of the code). Let's add a new rule to make our linting tighter.

[regexowl]

Originally added all autofix changes, but those break the service. We're combining optional chaining and type assertion in some cases. Meaning we ignore the possibility of undefined values, but when we get one everything crashes. Fun. 🙃

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.66%. Comparing base (8d34f85) to head (fb0248e).
Report is 1 commits behind head on main.

@@           Coverage Diff           @@
##             main    #2755   +/-   ##
=======================================
  Coverage   84.66%   84.66%           
=======================================
  Files         186      186           
  Lines       20996    20996           
  Branches     2033     2033           
=======================================
  Hits        17777    17777           
  Misses       3197     3197           
  Partials       22       22           

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8d34f85...fb0248e. Read the comment docs.

[lucasgarfield]

I love it! This is going to really help the review process - one less thing to look for!

[lucasgarfield]

My IDE is clever, I'm usually not (especially when I copy over a part of the code). Let's add a new rule to make our linting tighter.

Hard disagree on the second part 😉