You don't need autodie. You can rewrite your code so that it checks for errors and reports the reason for failure, e.g.:

open my $INFILE, '<', $infilename or die "Cannot open $infilename: $!"
+;
seek $INFILE, $readoffset, 0 or die "Cannot seek: $!";
open my $OUTFILE, '>>', $outfilename or die "Cannot open $outfilename:
+ $!";
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