Weird suitescript error

{
  "type": "error.SuiteScriptError",
  "name": "UNEXPECTED_ERROR",
  "message": null,
  "stack": [
    "anonymous(N/serverRecordService)",
    "<anonymous>(/SuiteScripts/set_backorder_eta.js:323)",
    "execute(/SuiteScripts/set_backorder_eta.js:231)"
  ],
  "cause": {
    "type": "internal error",
    "code": "UNEXPECTED_ERROR",
    "details": null,
    "userEvent": null,
    "stackTrace": [
      "anonymous(N/serverRecordService)",
      "<anonymous>(/SuiteScripts/set_backorder_eta.js:323)",
      "execute(/SuiteScripts/set_backorder_eta.js:231)"
    ],
    "notifyOff": false
  },
  "id": "0fc231ac-c1c8-42c8-b4e5-663b98552f75-2d323032332e30322e3234",
  "notifyOff": false,
  "userFacing": false
}

when using the code: The line in reference in the error is the salesorder.setSublistValue, any reason?

make sure that you are setting the right data type

I have the same set of lines running for a different if/else statemetn