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/maps1/11613/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-d2ff2b13-09fa-4514-a2ee-42cece2c0ebd",
      "cw-6998bdc9-5887-4e2d-8787-5dbd3c2d5b89"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-03206756-601b-4952-b990-2c7cf9e2c0e6",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/11613/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-6998bdc9-5887-4e2d-8787-5dbd3c2d5b89"
  }
}