$ cat ex.pl
#!/usr/bin/env perl
use warnings;
use strict;

END { $? = 250 if $? == 255 }

print $c;

$ perl ex.pl ; echo $?
Global symbol "$c" requires explicit package name (did you forget to declare "my $c"?) at ex.pl line 7.
Execution of ex.pl aborted due to compilation errors.
250