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/maps1/30086/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-830dbecb-e82e-4314-9fd8-33fd9020905b",
      "cw-7b064183-6243-4075-a6ad-5c8fd1c06d75"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-3345f8aa-5d69-4c87-afcb-e3c52343a99f",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/30086/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-7b064183-6243-4075-a6ad-5c8fd1c06d75"
  }
}