line 24 - remove double " 
#open my $fileone, '<', "$folder/$file" or die ""$folder/$file": $!";
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In case it isn't obvious to anyone reading this, the problem with die ""$folder/$file": $!"; is that there's nothing to say that the second " is a literal character and not simply closing the empty string started by the first " character. Here are some alternatives:

die "'$folder/$file': $!";    # choose a different literal character
die "\"$folder/$file\": $!";  # escape the inner "
die qq{"$folder/$file": $!};  # use an alternative outer delimiter
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