fs.util's promisify() method exists but causes error in DukTape

[lll000111]

"util" is green on https://www.lowjs.org/documentation/nodejs-api.html and promisify exists.

I tried promisifying a few functions in fs and got

> var readFile = promisify(fs.readFile);
TypeError: undefined not callable (property 'getOwnPropertyDescriptors' of [object Function])
    at [anon] (deps/duktape/src-low/duktape.c:64945) internal
    at promisify (lib:internal/util:294) strict
    at global (repl:1) preventsyield
    at [anon] () native strict preventsyield
    at [anon] (lib:vm:26) strict
    at defaultEval (lib:repl:260) strict
    at onLine (lib:repl:511) strict
    at emit (lib:events:158) strict
    at [anon] (lib:readline:231) strict
    at [anon] (lib:readline:530) strict
    at [anon] (lib:readline:773) strict
    [...]

PS: This is not urgent, I was just curious and experimenting.