I don't get this error with my own implementation of reduce:

#!/usr/bin/perl -w

use vars qw($a $b);

sub myreduce(&@)
{
  my $sub = shift;
  $a = shift;
  
  foreach $b (@_)
  {
    $a = $sub->();
  }
  $a;
}

print myreduce{ eval "$a + $b" } 1,2,3;
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