Return zero value as exit code when don't hit anything

[babarot]

Thank you for developing useful CLI tool!

Now, jvgrep returns zero value as exit code even if doesn't hit anything:

$ cat *.csv | jvgrep あ
$ echo $?
0

I want jvgrep to return non-zero like grep:

$ cat *.csv | grep a
$ echo $?
1

[babarot]

Thanks