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/1097/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-eeed5553-03e4-47e4-99c6-8b4b9ed1cf69",
      "cw-79d093b2-4de4-4d95-b07b-6af7eaa0fbee"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-1de292cc-b2a8-477e-9886-f0d85b6bc306",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/mgs/1097/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-79d093b2-4de4-4d95-b07b-6af7eaa0fbee"
  }
}