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/maps1/27068/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-cb51c87f-c3f1-43a3-9f2e-c912d5ad5f5a",
      "cw-78c01477-7059-498d-bb90-0152d7c8b7e0"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-5775d3c7-e696-429f-b5e8-c7600a7c8df8",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/27068/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-78c01477-7059-498d-bb90-0152d7c8b7e0"
  }
}