RuntimeError (panic) in JSX parser when encountering surrogate entitie

[cuyl]

Describe the bug

Got an error: RuntimeError: unreachable

Input code

"use client";

export default function Hello() {
  return (
   <div title="&#xD83E;&#xDD80;&#xDD80;&#xDD80;&55358;&56704;" >&#xD83E;&#xDD80;</div>
  );
}

Config

{
  "jsc": {
    "parser": {
      "syntax": "ecmascript",
      "jsx": true
    },
    "target": "es2024",
    "loose": false,
    "minify": {
      "compress": false,
      "mangle": false
    }
  },
  "module": {
    "type": "es6"
  },
  "minify": false,
  "isModule": true
}

Link to the code that reproduces this issue

https://play.swc.rs/?version=1.15.26&code=H4sIAAAAAAAAA2XMwQrCMBCE4fs%2BxRBB2pOFGg2k7amCryHtFgIhKXFTCuK7G696%2BuYyv8pPxuQdB1GWiPc1JsHMyyN7wZLDJC4G3Nn7WNV4EZBYcgqoykQ3uw3ixHOvjod9NO3Nfh1N86%2FWrTaFy7U5W4Xh99CdSm0o2drSmz7AIZCMmgAAAA%3D%3D&config=H4sIAAAAAAAAA1WPSw7DIAxE9zkF8rqLKqq66B16CIs6ERE%2FYSIVRbl7CQHa7vCbGcbeBiFgYQkPseVnHjwGptDnTDjZiO9MgKRBlkH5CJemLnxIMaxUyH4KEDHMFEuIx%2Bt4qwHQzjFlPKFmqswoq6b0Wymd8YGY%2F42HFe2se%2F5sHGorGPdai1hPicnTucEdvqZW1j8Gxc%2BWLHfsH%2BoMFmcWAQAA

SWC Info output

No response

Expected behavior

The parser should:

1. Support UTF-16 surrogate pairs represented as consecutive JSX entities (e.g., "��" should decode to 🦀).
2. Handle invalid or unpaired surrogates gracefully without panicking.
3. Return a SyntaxError instead of panicking if a numeric entity value is invalid.

Actual behavior

No response

Version

1.15.26

Additional context

No response