FYI (if you ever want to make one), the JSON file looks like this:

{
"name": "image",
"size": [64, 64],
"clips": [
    { "name": "neutral", "frames": [0], "loop": "no", "fps": 0 },
    { "name": "happy", "frames": [1], "loop": "no", "fps": 0 },
    { "name": "barely", "frames": [2], "loop": "no", "fps": 0 },
    { "name": "missed", "frames": [3], "loop": "no", "fps": 0 }
]
}

This file is accompanied with image.png, which is the sprite sheet. It has to be arranged vertically (not horizontal)

I’ve made a sample sprite here: https://file.garden/ZP2W5NRM-w48DgLF/smile.zip