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/maps1/10705/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-3ece9446-4040-41c3-b772-cc7cc8c1099c",
      "cw-24702d2e-507e-4bf2-8637-37c2eb676a5b"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-4c00654d-7e26-4666-8cf8-4afc7817b31f",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/10705/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-24702d2e-507e-4bf2-8637-37c2eb676a5b"
  }
}