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/maps1/14003/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-5d306320-87ce-469c-b9ee-bff57714ff93",
      "cw-625b87c2-6537-4aae-a432-4106b7443953"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-20927b3f-0e1f-4ba5-9121-cab66be2175b",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/14003/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-625b87c2-6537-4aae-a432-4106b7443953"
  }
}