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/1047/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-c82ab0dc-8302-4b34-85a5-3ec4e52bb6c2",
      "cw-b07d4fd9-67b0-4d5a-9982-ce9dd6467b4d"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-957de762-7fe4-46bb-aa41-5424f798978e",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/mgs/1047/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-b07d4fd9-67b0-4d5a-9982-ce9dd6467b4d"
  }
}