Return success

  wp_send_json_success(['found' => true]);

  wp_send_json_success(
    [
      "proofId" => $UniqueIdString,
      "storage" =>
      [
        "OperationId" => $OperationId,
        "imageCount" => $ImageCount
      ]
    ]
  );
  //No need to use die();, wp_send_json_success exits the handling of the AJAX call

Return an error

  wp_send_json_error(['message' => 'Invalid location code format.']);

  wp_send_json_error(
    [
      "error"=>"Failed to save metadata JSON"
    ],
    500
  );
  //No need to use die();, wp_send_json_error exits the handling of the AJAX call