Manifest is not valid JSON. Line: 1, column: 1, Unexpected token

keep getting this error: “Manifest is not valid JSON. Line: 1, column: 1, Unexpected token.” i don’t understand what the issue is with my code? here is what i have so far:

{
    "manifest_version": 2,
    "name": "extension",
    "version": "1.0",
    "description": "My first Chrome extension.",
    "browser_action": {
        "default_icon": "icon.jpg",
        "popup": "popup.html"
    }
}