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:2766/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-c4e4c001-ebd4-467c-9bf4-44bf1af10bf7",
      "cw-7cd8cdcf-054c-43c8-bd62-35ed4605d2df"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-88f53b63-2eb5-4cfd-8071-e4278fb5aeb0",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/nemhc:2766/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-7cd8cdcf-054c-43c8-bd62-35ed4605d2df"
  }
}