This entire HTML’s script code:

    [...document.querySelectorAll("input")].forEach(ele => {
    ele.addEventListener(
        "change", () => {
            Main();
        }
    );
});

function Main() {
    document.getElementById("Output").textContent = ""
    
    [...document.querySelectorAll("*.HiddenMsg")].forEach(ele => ele.hidden = true)
    try {
        let DatesWrong = false
        let StartDate = new Date(document.getElementById("Input_DateTimeStart").value)
        if (StartDate.toString() == "Invalid Date") {
            document.getElementById("Input_DateTimeStart_ErrorMsg").hidden = false
            DatesWrong = true
        }
        let EndDate = new Date(document.getElementById("Input_DateTimeEnd").value)
        if (EndDate.toString() == "Invalid Date") {
            document.getElementById("Input_DateTimeEnd_ErrorMsg").hidden = false
            DatesWrong = true
        }
        if (DatesWrong) {
            return
        }
        
        let TimeDiff = EndDate.valueOf() - StartDate.valueOf()
        if (TimeDiff < 0) {
            document.getElementById("Output").textContent = "End date before start."
            return
        }
        let DurationString = DisplayTimeDuration(TimeDiff)
        
        document.getElementById("Output").textContent = "Duration: " + DurationString + " (" + TimeDiff.toFixed(0) + " ms)"
    } catch {
        return
    }
}
function DisplayTimeDuration(Duration) {
    let OutputString = ""
    
    Duration = Math.abs(Duration)
    
    let UnitsOfTimeArray = []
    let Seconds = Math.floor(Duration/1000)
    UnitsOfTimeArray.unshift({Unit: Seconds % 60, UnitName: "s"})
    
    let Minute = Math.floor(Seconds/60)
    UnitsOfTimeArray.unshift({Unit: Minute % 60, UnitName: "m"})
    
    let Hour = Math.floor(Minute/60)
    UnitsOfTimeArray.unshift({Unit: Hour % 24, UnitName: "h"})
    
    let Day = Math.floor(Hour/24)
    UnitsOfTimeArray.unshift({Unit: Day, UnitName: "d"})
    
    let LeadingUnitIsNonZero = false
    for (let i = 0; i < UnitsOfTimeArray.length; i++) {
        if (UnitsOfTimeArray[i].Unit != 0) {
            LeadingUnitIsNonZero = true //Once it's true, stays true. All remaining units are significant
        }
        if (LeadingUnitIsNonZero || i == UnitsOfTimeArray.length-1) {
            OutputString += UnitsOfTimeArray[i].Unit + UnitsOfTimeArray[i].UnitName
            if (i != UnitsOfTimeArray.length-1) {
                OutputString += " "
            }
        }
    }
    return OutputString
}

The code [...document.querySelectorAll("*.HiddenMsg")].forEach(ele => ele.hidden = true), for whatever reason, errors out saying Uncaught SyntaxError: Unexpected token '...', however, when I change that line of code to have a identifier like this: let test = [...document.querySelectorAll("*.HiddenMsg")].forEach(ele => ele.hidden = true), it works fine. Any idea why this bug false-positively say there’s a syntax error with the spread syntax? The very literal first line of code have no issues whatsoever.