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/info/mgs/1022/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-5a253ee6-aa4e-48eb-941e-c802b1afe5b8",
      "cw-4ad609b7-7de9-4e3b-a0c6-87007bdfd709"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-99b9e65f-e753-4f65-b81c-0454601d278f",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/mgs/1022/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-4ad609b7-7de9-4e3b-a0c6-87007bdfd709"
  }
}