your code should work fine , it dies because the file you

want to extract is actually not inside the archive

you'll need to add extra code to check if the file found or not

 
#After this code 
my $member = $somezip->memberNamed( 'unzipped.txt'  );
# Add this line 
if ( not defined $member ) {
die "File not found inside the archive";
}else{ 
# the rest of your code goes here 
}
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by the way your code actually take the file from one archive file to another one