Mirador viewer

SyntaxError: Unexpected token 'I', "I don't kn"... is not valid JSON

{
  "manifest": {
    "error": "SyntaxError: Unexpected token 'I', \"I don't kn\"... is not valid JSON",
    "id": "https://iiif.participatory-archives.ch/SGV_12S_01951/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-553fbb96-dd8d-4041-912f-2c652338d308",
      "cw-afac7186-6448-48b0-adc7-6dfd09137d1f"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-9fafd1a5-ac45-4194-8165-6cb8ee169e1e",
    "manifestId": "https://iiif.participatory-archives.ch/SGV_12S_01951/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": true,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-afac7186-6448-48b0-adc7-6dfd09137d1f",
    "loadedManifest": "https://iiif.participatory-archives.ch/SGV_12S_01951/manifest.json"
  }
}