line 17: warning: command substitution: ignored null byte in input [BASH]

Im beginer with Bash script, i wanna ask with my error code .

cari.sh: line 17: warning: command substitution: ignored null byte in input

Line : 17 is

GET=$(curl --silent --max-time 10 --connect-timeout 10 -L "${Website}")

Im got Error when i using Looping and with Multithread like this :

IFS=$'\r\n'
n=1
t=3
for Website in $(cat $WEB); do
        f=$(expr $n % $t)
        if [[ $f == 0 && $n > 0 ]]; then
                sleep 1
        fi
        RUN $TARGET $n &
        n=$[$n+1]
done
wait

And then im using 2 > /dev/null , and try run script, and im same got error .