There is no error because the exit value for "cat $file | wc -l" is 0 (zero).

Change the command to "wc -l file", as you say, and you get the error.

use IPC::System::Simple qw( capture $EXITVAL);
use strict;
use warnings;
use Try::Tiny;

my $file = 'foo';

my $result;
try {
    $result = capture("cat $file | wc -l");
}
catch {
    print "Error: $_";
};
print "Exitval is $EXITVAL";
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