Mirador viewer

SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON

{
  "manifest": {
    "error": "SyntaxError: Unexpected token '<', \"<!DOCTYPE \"... is not valid JSON",
    "id": "https://digital.libraries.psu.edu/iiif/info/maps1/14186/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-3e339ca8-21b0-4053-b106-a604a2acaaad",
      "cw-7a303d55-3894-4326-afb9-616213b92871"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-9e633699-4a3b-4d12-b271-23941b045515",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/14186/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-7a303d55-3894-4326-afb9-616213b92871"
  }
}