An issue about type of NaN

[NWU-NISL]

According to the output of line 6, we can know that the value of hours is NaN, so its type should be number instead of string.

JerryScript version

9ab4872

Build platform

Ubuntu 16.04.6 LTS (Linux 4.15.0-55-generic x86_64)

Build steps

python tools/build.py --clean --debug --logging=on --line-info=on --error-messages=on --cpointer-32bit=on --mem-heap=1572864 --profile=es2015-subset

Test case

var NISLFuzzingFunc=function (nislMutationParameter0){
    var date = new Date(); 
    var a = date.setHours(nislMutationParameter0);
    print(a);
    var hours = date.getHours();
    print(hours);
    print(typeof hours);
};
var nislMutationArgumenter0 = "-";
NISLFuzzingFunc(nislMutationArgumenter0);

Execution steps

build/bin/jerry testcase.js

Output

NaN
NaN
string

Expected behavior

NaN
NaN
number