Take ESLint 10 and react-hooks 7, and drop two dead assignments they found

[fstubner]

Supersedes #180 (eslint), #182 (@eslint/js) and #179 (eslint-plugin-react-hooks).

None of the three could merge alone — @eslint/js 10 peer-depends on eslint@^10, so they move together.

Nothing else was blocking them

package	peer range	satisfied
typescript-eslint 8.67	eslint: ^8.57.0 || ^9.0.0 || ^10.0.0	yes
eslint-plugin-react-hooks 7.1.1	eslint: … || ^10.0.0	yes
eslint 10.8.1	node: ^20.19.0 || ^22.13.0 || >=24	yes — via the Node 22 move in #187

The config needed no changes. Note the last row: on the old Node 20 runner this bump would have been blocked too, for the same reason jsdom was.

What the upgrade found

no-useless-assignment is new in ESLint 10's recommended set, and it caught two real dead assignments — same shape in both places:

let next = current;
switch (event.key) {
  case 'ArrowDown': next = ...; break;   // every arm assigns
  default: return;                       // ...or returns
}

The seed value can never be read. Both are now declared without an initialiser, so the compiler enforces "every path assigns or returns" instead of a plausible-looking default quietly absorbing a missing case. tsc accepting it is the proof that the property actually holds.

Verification

The rule set still fires — checked rather than inferred from a green exit. A throwaway probe file containing a conditional hook, an any, and a bad dependency array produced all three diagnostics:

error    Unexpected any                                 @typescript-eslint/no-explicit-any
error    React Hook "useState" is called conditionally  react-hooks/rules-of-hooks
warning  useEffect has a missing dependency             react-hooks/exhaustive-deps

That matters here because a major-version bump that silently stopped registering the plugin would still exit 0, and react-hooks is the rule set that catches the stale-closure bugs this project has actually shipped.

Lint: 0 errors, 3 warnings — the same three pre-existing exhaustive-deps warnings as before. 94 tests and the build pass.

Still blocked

#134 (TypeScript 7) is unaffected. typescript-eslint 8.67 caps TypeScript at >=4.8.4 <6.1.0, so no ESLint-side bump helps it.