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/p16022coll624/399/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-8bd12f68-ee52-4050-9b71-a12fc599e27d",
      "cw-a43dc3e3-23fd-4f55-9e11-f3353bfa5716"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-88c8624c-bd8b-4d87-a202-4730e77b630e",
    "manifestId": "https://cdm16022.contentdm.oclc.org/iiif/info/p16022coll624/399/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-a43dc3e3-23fd-4f55-9e11-f3353bfa5716"
  }
}