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_00921/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-216942f4-1dc0-49d0-be85-39fbc0d8d944",
      "cw-3d1df793-25f9-4e93-baf2-68abf581d1ef"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-1a911f07-4919-4b26-8df8-8c027e42b5f0",
    "manifestId": "https://iiif.participatory-archives.ch/SGV_12S_00921/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": true,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-3d1df793-25f9-4e93-baf2-68abf581d1ef",
    "loadedManifest": "https://iiif.participatory-archives.ch/SGV_12S_00921/manifest.json"
  }
}