fix(pkg): fix duplicate configuration warning logic

[ho991217]

• This PR contains AI-generated code, but I have carefully reviewed it myself. Otherwise, my PR may be closed.

Description

bundleDone() crashes with TypeError: Cannot read properties of undefined (reading 'logger') when only one of publishConfigs / attwConfigs has length > 1. Falls back to whichever side actually has the duplicate so the warning can be emitted safely.

dedupeConfigs(configs, 'publint') collapses to length 1 because publint: true is filtered out and falls through to [filtered[0]].
However, dedupeConfigs(configs, 'attw') keeps length 2 because each entry's attw is a fresh literal and dedupe is reference-based. The OR-guarded warning then derefereces publintConfig[1] and throws

Repro

import { defineConfig } from 'tsdown';

export default defineConfig([
  { entry: "./a.ts", publint: true, attw: { profile: 'esm-only' } },
  { entry: "./b.ts", publint: true, attw: { profile: 'esm-only' } },
]);

Linked Issues

Additional context

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commit: 8871403

[Copilot]

Pull request overview

Fixes a crash in the package bundling completion flow when duplicate configuration warnings are emitted and only one of publint/attw has multiple configs for a package.

Changes:

• Adjust duplicate config warning logic to select an available duplicate config (publint or attw) before logging.
• Prevent TypeError: Cannot read properties of undefined (reading 'logger') in bundleDone() when only one side has duplicates.

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