Assuming that the lines in errort.log already have newelines at the end, and assuming you want to print the entire file, you can further simplify this as:

...
open(LOG, "<$logfile") or die "$logfile: $!";
print "<pre>";
print <LOG>;
print "</pre>\n";
close(LOG);
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Update: Reasonable people are disagreeing on how to interpret your question. Please clarify: Are the warnings you want to avoid seeing 1) produced by the script, or 2) in the logfile?