chore(deps): eslint 10, and the leak it found - #25
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The bump itself is clean — no config changes, no rule renames. What it costs is three findings from rules that are new in this major, and one of them is a real bug. MermaidDiagram declared a `themeObs` in onMount and disconnected it in the teardown, while the effect that actually creates the observer declared a SECOND one inside its own scope. The outer binding was never assigned, so the cleanup disconnected nothing: every diagram scrolled past left a MutationObserver watching `document.documentElement` for the life of the page. The media-query listener beside it was never removed either. Both now live at component scope where the teardown can reach them, and `no-unassigned-vars` is what surfaced it. The other two are dead initialisers — a `passed = false` and a `note = null` that every path overwrites or returns before reading. Removing them is not tidying: it means a branch added later that forgets to assign fails to compile, instead of silently taking the initial value. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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The bump itself is clean: no config changes, no rule renames, no flat-config migration. What it costs is three findings from rules that are new in this major — and one of them is a real bug.
The leak
MermaidDiagramdeclared athemeObsinonMountand disconnected it in the teardown. The effect that actually creates the observer declared a second one inside its own scope, shadowing it. So the outer binding was never assigned, the cleanup disconnected nothing, and every diagram scrolled past left aMutationObserverwatchingdocument.documentElementfor the life of the page. The media-query listener beside it was never removed either.no-unassigned-varsis what surfaced it — "always undefined because it's never assigned". Both watchers now live at component scope where the teardown can reach them. Verified the diagram still re-themes on toggle, which is the behaviour the observer exists for.The other two
Dead initialisers — a
passed = falseand anote = nullthat every path overwrites or returns before reading. Removing them isn't tidying: it means a branch added later that forgets to assign fails to compile, instead of silently taking the initial value.492 unit, 62 e2e, lint, type-check and build clean.
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