🔧 Add import/no-duplicates lint rule

[TheAfroOfDoom]

Summary

In #1180 I noticed that my duplicate import statements weren't being caught by the linter. There's (at least) two lint rules that exist that can detect/fix these easily, so this PR's primary purpose is to add one of those lint rules.

ESLint's built-in rule relating to duplicate imports no-duplicate-imports doesn't have auto-fix for some reason. So instead we went with the eslint-plugin-import plugin which has import/no-duplicates (which can auto-fix these errors).

sample rule error/auto-fix

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Supplemental changes

I was also getting errors when I was running npm run lint due to our @typescript-eslint version not supporting our my local TS version (5.4).

G:\Coding\Spyglass [main]> npm run lint

> @spyglassmc/root@1.0.0 lint
> eslint --cache --max-warnings=0 packages/*/{src,test}/**/*.{cts,mts,ts}

=============

WARNING: You are currently running a version of TypeScript which is not officially supported by @typescript-eslint/typescript-estree.

You may find that it works just fine, or you may not.

SUPPORTED TYPESCRIPT VERSIONS: >=3.3.1 <5.1.0

YOUR TYPESCRIPT VERSION: 5.4.5

Please only submit bug reports when using the officially supported version.

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So I updated @typescript-eslint to the latest major version v7.9 (since v7.0 was the minimum version with TS 5.4 support anyway).

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Upgrading @typescript-eslint to v7.9 led to some Unsupported engine warnings whenever I'd run an npm command:

I had node v18.17.1 installed locally, but we didn't actually specify anywhere a minimum node version for the Spyglass repo as a whole.

So I went with @typescript-eslint's recommended versions (listed in that warning above): ^18.18.0 || >=20.0.0

• ^18.18.0 is LTS
• >=20.0.0 is any modern node version

These engines felt like a reasonable requirement. Upgrading my local node to v18 LTS (v18.20.2) resolved these engine discrepancy warnings with @typescript-eslint.

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I think after updating @typescript-eslint to support my local Typescript version, the @typescript-eslint/prefer-readonly began to emit warnings it had not previously. So I included those auto-fixes in this PR as well: ef9d9c1 (#1181).

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Unrelated, we forgot to run npm i after updating mcdoc-cli from 0.1.3 to 0.1.5. So I did that to keep our package-lock.json up-to-date in d3f9713 (#1181).

[NeunEinser]

Would it be possible to add a rule for unnecessary imports as well?

[TheAfroOfDoom]

Would it be possible to add a rule for unnecessary imports as well?

I'm not sure what you mean by this specifically, but the plugin I added eslint-plugin-import has a bunch of other import lint rules. feel free to look through that and see if it has what you're looking for

[NeunEinser]

I mean this situation.

Ideally, you wouldn't be allowed to commit this. It can happen quite easily when changing code and forgetting to delete these imports is quite easy.

I skimmed through the possible rules there and didn't see anything immediately.

[SPGoding]

https://eslint.org/docs/latest/rules/no-unused-vars probably works for unused vars in import

[SPGoding]

The @spyglassmc/mcdoc-cli version really should just be 0.1.0-PLACEHOLDER in package.json like every other package in this repository since the version is set by the release script and should not be changed manually.