Error when making a JSON patch

[MAZ12211]

I want to make an extra difficulty for a mod from another mod using _merge logic, but I don't understand what this error means

// filename: blissful-metadata.json
// path: mod/_merge/data/songs/blissful
[
  {
    "op": "add",
    "path": "/playData/difficulties/0",
    "value": "easy,"
  },
  {
    "op": "add",
    "path": "/playData/ratings/-",
    "value": {
      "easy": 3
    }
  }
]

Here's the original file

{
  "version": "2.2.4",
  "songName": "Blissful",
  "artist": "Biddle3",
  "charter": "FatzFries",
  "divisions": 96,
  "looped": false,
  "offsets": {
    "instrumental": 0,
    "altInstrumentals": {    },
    "vocals": {    },
    "altVocals": {    }
  },
  "playData": {
    "songVariations": [    ],
    "difficulties": [
      "normal",
      "hard"
    ],
    "characters": {
      "player": "BF-QT",
      "girlfriend": "GF-QT",
      "opponent": "QT",
      "instrumental": "",
      "altInstrumentals": [      ],
      "opponentVocals": [
        "QT"
      ],
      "playerVocals": [
        "BF-QT"
      ]
    },
    "stage": "trashAlleyQt",
    "noteStyle": "funkin",
    "ratings": {
      "hard": 6,
      "normal": 4
    },
    "album": "qt",
    "previewStart": 0,
    "previewEnd": 0
  },
  "generatedBy": "Friday Night Funkin' - v0.5.3",
  "timeFormat": "ms",
  "timeChanges": [
    {
      "t": 0,
      "b": 0,
      "bpm": 138,
      "n": 4,
      "d": 4,
      "bt": [
        4,
        4,
        4,
        4
      ]
    }
  ]
}

[moxie-coder]

I want to make an extra difficulty for a mod from another mod using _merge logic, but I don't understand what this error means

// filename: blissful-metadata.json
// path: mod/_merge/data/songs/blissful
[
  {
    "op": "add",
    "path": "/playData/difficulties/0",
    "value": "easy,"
  },
  {
    "op": "add",
    "path": "/playData/ratings/-",
    "value": {
      "easy": 3
    }
  }
]

Here's the original file

{
  "version": "2.2.4",
  "songName": "Blissful",
  "artist": "Biddle3",
  "charter": "FatzFries",
  "divisions": 96,
  "looped": false,
  "offsets": {
    "instrumental": 0,
    "altInstrumentals": {    },
    "vocals": {    },
    "altVocals": {    }
  },
  "playData": {
    "songVariations": [    ],
    "difficulties": [
      "normal",
      "hard"
    ],
    "characters": {
      "player": "BF-QT",
      "girlfriend": "GF-QT",
      "opponent": "QT",
      "instrumental": "",
      "altInstrumentals": [      ],
      "opponentVocals": [
        "QT"
      ],
      "playerVocals": [
        "BF-QT"
      ]
    },
    "stage": "trashAlleyQt",
    "noteStyle": "funkin",
    "ratings": {
      "hard": 6,
      "normal": 4
    },
    "album": "qt",
    "previewStart": 0,
    "previewEnd": 0
  },
  "generatedBy": "Friday Night Funkin' - v0.5.3",
  "timeFormat": "ms",
  "timeChanges": [
    {
      "t": 0,
      "b": 0,
      "bpm": 138,
      "n": 4,
      "d": 4,
      "bt": [
        4,
        4,
        4,
        4
      ]
    }
  ]
}

1, JSON cannot have comments
2, the error is literally right in front of your eyes

[MAZ12211]

But the documentation says - is the last index of the array which is what I want and when I even tried putting it in the second index (1), I got same result

Comments are just for clarification, they aren't in the JSON file

[AbnormalPoof]

ratings is not an array.