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/maps1/5000/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-93c13824-cb2c-4138-96bd-6604dd63a51d",
      "cw-65b97acc-919d-41d5-9415-34af6a19dc45"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-1a3936ba-40ae-4909-bdaf-0d66b5cfc39e",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/5000/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-65b97acc-919d-41d5-9415-34af6a19dc45"
  }
}