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/892/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-8a32d784-7750-46c7-83f9-a350a078cdac",
      "cw-eef820d7-96da-446a-a81e-11ead2718e77"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-a4b8cda9-e51b-4bb1-86d0-de90f0a607fa",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/mgs/892/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-eef820d7-96da-446a-a81e-11ead2718e77"
  }
}