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/1024/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-7d8b3a6d-a378-41e4-b6fe-2b7f563c4b57",
      "cw-40f4b91f-b5a9-4726-b964-e657f6ed8b4c"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-5e3cd292-683a-4e42-a3e6-e0c9e15ce2b5",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/mgs/1024/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-40f4b91f-b5a9-4726-b964-e657f6ed8b4c"
  }
}