node, 59 bytes

Result

WA

Code [DL]

console.log(require('fs').readFileSync().sort().toString())

stdin

9748693831118106511455512828787573280627755387849668766894753980560234338139106053667749818529195938

stdout

stderr

fs.js:584
  return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
                 ^

TypeError: path must be a string or Buffer
    at Object.fs.openSync (fs.js:584:18)
    at Object.fs.readFileSync (fs.js:491:33)
    at Object.<anonymous> (/volume/CODE:1:89)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.runMain (module.js:605:10)
    at run (bootstrap_node.js:427:7)

strace