Visual Studio Code snippet invalid control character

I have the following user snippet:

{
/*
    // Place your snippets for JavaScript React here. Each snippet is defined under a snippet name and has a prefix, body and 
    // description. The prefix is what is used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
    // $1, $2 for tab stops, $0 for the final cursor position, and ${1:label}, ${2:another} for placeholders. Placeholders with the 
    // same ids are connected.
    // Example:
    "Print to console": {
        "prefix": "log",
        "body": [
            "console.log('$1');",
            "$2"
        ],
        "description": "Log output to console"
    }
*/
    "Small comment": {
        "prefix": "//=",
        "body": [
            "// ===================================",
            "// ${1:COMMENT}",
            "// ==================================="
        ],
        "description": "Small comment"
    }
}

I get the following error on the second body line:

Invalid characters in string. Control characters must be escaped.

I thought that ${1:somestring} was a valid placeholder. What am I doing wrong in constructing this snippet?