Mirador viewer

SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON

{
  "manifest": {
    "error": "SyntaxError: Unexpected token '<', \"<!DOCTYPE \"... is not valid JSON",
    "id": "https://digital.libraries.psu.edu/iiif/info/maps1/30024/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-5c9042de-8725-4bb5-8afb-0f5380a9f2d0",
      "cw-eb34688a-1705-4888-96b3-35cef7288ee4"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-523609e3-93f8-4074-a0e7-b620d457071e",
    "manifestId": "https://digital.libraries.psu.edu/iiif/info/maps1/30024/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-eb34688a-1705-4888-96b3-35cef7288ee4"
  }
}