EXIF.getData() function always returns an empty string and “undefined”

I’m developing a simple Chromium extension that reads EXIF data and shows to the user but in the library I’m using (which is Exif.js), I feel like there are things I’m not doing correctly because the output is always an empty string and undefined. Here’s the code:

const img = document.getElementById("someImage");

window.onload = getExif(img);

function getExif(file) {
    try {
        EXIF.getData(file, function () {
            if (file) {
                var make = EXIF.getTag(this, "Make");
                var model = EXIF.getTag(this, "Model");
                var allMetaData = EXIF.pretty(this);

                console.log(JSON.stringify(allMetaData, null, 2));
                console.log(make, model);
            } else {
                console.error("EXIF data has not been found or incomplete.");
            }
        });
    } catch (error) {
        console.error("Error reading EXIF data", error);
    }
}

“make” and “model” always returns an “undefined” from an image I’m using through classical const img = document.getElementById(someImage) in popup.html as well as allMetaData returning and empty string.

I’ve followed the “Usage” section in the documentation but nothing appears to be fixing this.