build: fix lint errors and introduce CI check

[JustinBeckwith]

While working on a different task, I tried running npm run lint:fix in hopes of making sure my PR was clean and tidy. It generated ... a lot of unrelated changes. This PR does a few things:

• Runs npm run lint:fix to capture low hanging fruit
• Manually fixes issues standard couldn't automatically fix
• Introduces a new CI check to ensure the linter passes

Happy to discuss any changes!

[codecov-commenter]

Codecov Report

Merging #1277 (e6c090c) into main (5a0bf7e) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1277      +/-   ##
==========================================
- Coverage   94.11%   94.11%   -0.01%     
==========================================
  Files          44       44              
  Lines        4097     4096       -1     
==========================================
- Hits         3856     3855       -1     
  Misses        241      241              

Impacted Files	Coverage Δ
lib/fetch/index.js	77.66% <ø> (ø)
lib/llhttp/llhttp.wasm.js	100.00% <ø> (ø)
lib/llhttp/llhttp_simd.wasm.js	100.00% <ø> (ø)
lib/pool-stats.js	100.00% <ø> (ø)
lib/balanced-pool.js	97.61% <100.00%> (ø)
lib/core/connect.js	100.00% <100.00%> (ø)
lib/core/util.js	98.47% <100.00%> (ø)
lib/fetch/dataURL.js	96.52% <100.00%> (ø)
lib/fetch/util.js	76.00% <100.00%> (ø)
lib/mock/mock-interceptor.js	100.00% <100.00%> (ø)
... and 3 more

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[JustinBeckwith]

I'm at a bit of a loss .... npm run lint passes locally with the latest LTS release, but seems to be not passing in CI!? I'll keep poking, but wondering if others have any ideas.

[KhafraDev]

sameOrigin is a utility method exported in lib/fetch/util.js; error wasn't caught before because the previous condition isn't possible. It definitely isn't a global 😄.

edit: fixed in 09f00fb?

[JustinBeckwith]

yuuuuuup, that was it :) I was thinking "surely this isn't just broken" :)

[mcollina]

lgtm