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/953/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-2aea8689-9ce0-45c1-9d25-0c8cec18a99d",
      "cw-1d4fe71e-cf84-4d67-8e62-cf556c8fff87"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-0d198251-e1db-48c0-bc5e-75f032f2539f",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/mgs/953/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-1d4fe71e-cf84-4d67-8e62-cf556c8fff87"
  }
}