Silent saving image in electron.js

I have got problem with setting path to download files in this case for images. I download image from URL with blob construction like this:

async function downloadImage(imageSrc) {
    const image = await fetch(imageSrc)
    const imageBlog = await image.blob()
    const imageURL = URL.createObjectURL(imageBlog)

    const link = document.createElement('a')
    link.href = imageURL
    link.download = 'asd.png'
    document.body.appendChild(link)
    link.click()
    document.body.removeChild(link)
} 

Then i catch a download signal on main.js like this:

session.defaultSession.on("will-download", (event, item, webContents) => {
        item.setSavePath( /local_dir/ + item.getFilename());
    }) 

When i log getFilename() i have got correct filename what i want, silent also too works because i havent got a window to locate directory of download, but when i look into directory it is empty.

Thanks for help.