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/maps1/1014/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-1dd74675-8402-438a-9c12-46557a0e866c",
      "cw-c79bad03-294b-409e-b28e-f29e123823e4"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-14b4ed99-f057-4e9e-aa7d-9bb230e3086b",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/1014/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-c79bad03-294b-409e-b28e-f29e123823e4"
  }
}