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/maps1/3044/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-309cb328-f2cd-4f01-908c-2575fa65f86d",
      "cw-86237d84-4c11-4116-8e66-85912e34a726"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-b1e73299-77c9-4c7a-8ebf-84c63b1ca7c0",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/3044/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-86237d84-4c11-4116-8e66-85912e34a726"
  }
}