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/1084/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-8d79dc5b-c9a1-4d62-8848-ee7aa912ccbb",
      "cw-0a8d1bda-9d75-4cf1-8ba9-cd58f26f469e"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-413ebfe9-134c-46ec-8a47-99a90f714f8c",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/mgs/1084/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-0a8d1bda-9d75-4cf1-8ba9-cd58f26f469e"
  }
}