Laravel-datatables: PDF 내보내기 오류

문제 또는 기능 요청 요약

PDF를 내보낼 때 오류가 발생했습니다. 데모 사이트에서도 볼 수 있습니다.

http://dt54.yajrabox.com/buttons/eloquent?draw=1&columns%5B0%5D%5Bdata%5D=id&columns%5B0%5D%5Bname%5D=id&columns%5B0%5D%5Bsearchable%5D=true&columns%5B0%5D%5Borderable%5D=true&columns%5B0%5D%5Bsearch%5D%5Bvalue%5D=&columns%5B0%5D%5Bsearch%5D%5Bregex%5D=false&columns%5B1%5D%5Bdata%5D=name&columns%5B1%5D%5Bname%5D=name&columns%5B1%5D%5Bsearchable%5D=true&columns%5B1%5D%5Borderable%5D=true&columns%5B1%5D%5Bsearch%5D%5Bvalue%5D=&columns%5B1%5D%5Bsearch%5D%5Bregex%5D=false&columns%5B2%5D%5Bdata%5D=email&columns%5B2%5D%5Bname%5D=email&columns%5B2%5D%5Bsearchable%5D=true&columns%5B2%5D%5Borderable%5D=true&columns%5B2%5D%5Bsearch%5D%5Bvalue%5D=&columns%5B2%5D%5Bsearch%5D%5Bregex%5D=false&columns%5B3%5D%5Bdata%5D=created_at&columns%5B3%5D%5Bname%5D=created_at&columns%5B3%5D%5Bsearchable%5D=true&columns%5B3%5D%5Borderable%5D=true&columns%5B3%5D%5Bsearch%5D%5Bvalue%5D=&columns%5B3%5D%5Bsearch%5D%5Bregex%5D=false&columns%5B4%5D%5Bdata%5D=updated_at&columns%5B4%5D%5Bname%5D=updated_at&columns%5B4%5D%5Bsearchable%5D=true&columns%5B4%5D%5Borderable%5D=true&columns%5B4%5D%5Bsearch%5D%5Bvalue%5D=&columns%5B4%5D%5Bsearch%5D%5Bregex%5D=false&columns%5B5%5D%5Bdata%5D=action&columns%5B5%5D%5Bname%5D=action&columns%5B5%5D%5Bsearchable%5D=false&columns%5B5%5D%5Borderable%5D=false&columns%5B5%5D%5Bsearch%5D%5Bvalue%5D=&columns%5B5%5D%5Bsearch%5D%5Bregex%5D=false&order%5B0%5D%5Bcolumn%5D=0&order%5B0%5D%5Bdir%5D=desc&start=0&length=10&search%5Bvalue%5D=&search%5Bregex%5D=false&action=pdf

확인할 수 있도록 도와주세요.
감사 해요!