The problem lies with your split. @list contains things which aren't words, including 0-length strings.

Perhaps you should replace
my @list = split /[,.?!)"]?\s\)?/, shift;
with something like
my @list = shift =~ /([a-zA-Z'\-]+)/g;

$maxcount++;
should be
$maxcount = $count;

readline is poorly named. It doesn't read anything.

$hash{lc $word}++;
$count = $hash{lc $word};
can be simplified to
$count = ++$hash{lc $word};

sub read_file{ ... }
read_file @ARGV;
can be simplified to
while (<>) { read_line $_; }

In reply to Re: using hash to find frequency count by ikegami
in thread using hash to find frequency count by jjohhn

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