SyntaxError: Unexpected end of JSON input

{
  "manifest": {
    "error": "SyntaxError: Unexpected end of JSON input",
    "id": "https://earlyenglishlaws.ac.uk/eel_backend/manifests/m",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-c3d42ddd-ad52-4f48-86b1-9c2b01daf63b",
      "cw-cb5946b0-5879-4281-8c2a-b447444cddbf"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-491b4299-ccd8-4f69-9f3f-63e0499014a0",
    "manifestId": "https://earlyenglishlaws.ac.uk/eel_backend/manifests/m",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-cb5946b0-5879-4281-8c2a-b447444cddbf",
    "thumbnailNavigationPosition": "far-bottom",
    "allowClose": false,
    "hideWindowTitle": true,
    "allowFullscreen": false,
    "allowMaximize": false
  }
}