Mirador viewer

SyntaxError: Unexpected token 'E', "Error from"... is not valid JSON

{
  "manifest": {
    "error": "SyntaxError: Unexpected token 'E', \"Error from\"... is not valid JSON",
    "id": "https://iiif.participatory-archives.ch/SGV_10P_00034/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-f09d05f9-8bb9-48f0-aa9e-83c7db6541ea",
      "cw-beaf902c-dc78-4b29-a331-e211006a0f4c"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-48d9c2bf-b7a6-4879-b48b-5bc1e14cb3d9",
    "manifestId": "https://iiif.participatory-archives.ch/SGV_10P_00034/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": true,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-beaf902c-dc78-4b29-a331-e211006a0f4c",
    "loadedManifest": "https://iiif.participatory-archives.ch/SGV_10P_00034/manifest.json"
  }
}