Fix ESLint errors in component TypeScript

[myabc]

🤖 Opened by an agent on Alex's behalf.

What are you trying to accomplish?

npm run lint currently reports 7 ESLint errors on main. None of them are new; they accumulated as eslint-plugin-github moved to v6 and dropped rules the codebase still disables inline. This clears all of them so lint is a meaningful signal again, and so branches stacked on top start from a green baseline.

The errors:

• import/named — SelectStrategy and SelectVariant are types, not values, so import/named cannot resolve them from ./tree_view_sub_tree_node_element. Marked as type imports.
• custom-elements/no-dom-traversal-in-connectedcallback (×2) and custom-elements/no-constructor (×1) — eslint-disable comments for rules eslint-plugin-github v6 no longer ships, so ESLint errors on the unknown rule name. Removed.
• @typescript-eslint/no-unused-vars (×2) — CollapsibleHeaderElement and CollapsibleSectionElement are referenced only from the Window interface inside declare global, i.e. only in type position. Exported them.

What approach did you choose and why?

For the two no-unused-vars errors, export class follows the idiom already used by AvatarFallbackElement and FilterableTreeViewElement. Since primer.ts imports these modules for their side effects only, and neither is re-exported from the package entry point, the published API surface is unchanged.

The alternative — the if (!window.customElements.get('…')) { window.X = X; window.customElements.define('…', X) } block that several other components carry — was deliberately not used. With @controller, Catalyst's register() already calls customElements.define and assigns window[classObject.name] (swallowing the NotSupportedError for a duplicate definition), so by the time the module body runs the element is registered and the guard is always false. That block is dead code wherever it appears alongside @controller.

Removing the existing dead blocks is left out of scope on purpose: most of the files carrying them (alpha/*) come from upstream primer/view_components, and diverging there would create conflicts on every upstream sync.

Anything you want to highlight for special attention from reviewers?

Validation performed:

• npm run lint — 0 errors (stylelint + eslint)
• npx tsc --noEmit — clean
• script/build-assets js — bundle builds

Accessibility

• No new axe scan violation — no rendered markup, focus behavior, or accessibility semantics change; element registration behavior is identical.

Merge checklist

• Added/updated tests — not applicable; no behavior change
• Added/updated documentation — not applicable
• Added/updated previews (Lookbook) — not applicable

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#515 is stacked on this PR (base fix/eslint-component-typescript). Merge this one first; #515 then retargets to main.

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Latest commit: 6ce1691

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[Copilot]

Pull request overview

This PR cleans up TypeScript in Primer/OpenProject components to remove accumulated ESLint errors (notably after eslint-plugin-github v6), restoring npm run lint as a reliable signal without changing intended runtime behavior.

Changes:

• Convert SelectStrategy / SelectVariant imports in TreeView to type imports to satisfy import/named.
• Remove now-invalid inline eslint-disable directives for rules that are no longer shipped by the plugin.
• Export Catalyst controller classes that are otherwise only referenced in type positions (to satisfy @typescript-eslint/no-unused-vars).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
app/components/primer/open_project/zen_mode_button.ts	Removes an invalid eslint-disable comment around the custom element constructor.
app/components/primer/open_project/collapsible_section.ts	Exports the controller class to avoid no-unused-vars when used only in declare global.
app/components/primer/open_project/border_box/collapsible_header.ts	Exports the controller class to avoid no-unused-vars when used only in declare global.
app/components/primer/alpha/tree_view/tree_view.ts	Marks SelectStrategy/SelectVariant as type-only imports and removes invalid eslint-disable directives.

Suppressed comments (1)

app/components/primer/open_project/zen_mode_button.ts:14

• addEventListener/removeEventListener are using this.fullscreenChangeEventHandler.bind(this) inline. Each bind call creates a new function reference, so the listener added in the constructor is never removed in disconnectedCallback, which can leak listeners and cause duplicate event handling when elements are re-created.

    document.addEventListener('fullscreenchange', this.fullscreenChangeEventHandler.bind(this))
  }

  disconnectedCallback() {
    document.removeEventListener('fullscreenchange', this.fullscreenChangeEventHandler.bind(this))

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