Mirador viewer

SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON

{
  "manifest": {
    "error": "SyntaxError: Unexpected token '<', \"<!DOCTYPE \"... is not valid JSON",
    "id": "https://cdm16022.contentdm.oclc.org/iiif/nemhc:2808/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-58864050-d003-4a78-8d21-2115a4b3bdad",
      "cw-eed65a1f-890a-4959-959b-6cb33ae0e7e7"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-81980bdf-186e-4290-b300-656b7d9b4d11",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/nemhc:2808/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-eed65a1f-890a-4959-959b-6cb33ae0e7e7"
  }
}