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_01694/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-127b7944-b607-47e4-bc89-910e957072e0",
      "cw-938a3f89-5457-4c3c-b1c9-1cbbec775926"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-7a581346-a319-44ea-915f-ba5da7e4ce1b",
    "manifestId": "https://iiif.participatory-archives.ch/SGV_10P_01694/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": true,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-938a3f89-5457-4c3c-b1c9-1cbbec775926",
    "loadedManifest": "https://iiif.participatory-archives.ch/SGV_10P_01694/manifest.json"
  }
}