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2a2ba39ddb
`bundled.js` stopped being ES5 when the webpack build was replaced by tsdown in #628. It parses at ecmaVersion 2015 but not 5: var t=(t,e)=>()=>(e||(t((e={exports:{}}).exports,e),t=null),e.exports) That is rolldown's `__commonJS` interop helper. `@rolldown/plugin-babel` only transforms input modules, and rolldown appends the helper afterwards; terser with `ecma: 5` avoids introducing newer syntax but does not transpile, so the arrow functions reached the published file. `es5.js` has no CommonJS dependencies and never gets the helper, which is why only `bundled.js` broke. The effect is total rather than partial: in an ES5 engine the whole script is a SyntaxError, so `bundled.js` — the bundle that exists specifically to serve those engines, polyfills included — does not load at all there. Lower the emitted chunk with a babel renderChunk pass that runs after bundling and before terser, so rolldown's own helpers are covered too. Costs 2.8 kB (+1.6%) on bundled.js; es5.js is unchanged at 34 kB. The existing guard was a grep for backticks, which this syntax slips straight past. Replace it with an acorn parse at ecmaVersion 5 over both legacy bundles, plus a tokeniser check for real template literals (backticks inside core-js string literals are fine, and 2.14.1 shipped three of them). Verified by reverting the build fix: `bundled.js parses as ES5` fails, and passes again once restored. Also confirmed bundled.js loads and parses the live navigator.userAgent in a real browser.