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/maps1/14895/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-b4c9bae6-b889-43ab-a173-c8cbfd55ef22",
      "cw-bc3cfadd-04e1-4163-9bd4-6098a2643da3"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-b60a5982-8102-43c7-a4d8-9c26599290ea",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/14895/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-bc3cfadd-04e1-4163-9bd4-6098a2643da3"
  }
}