title: Use of uninitialized value in subroutine entry at mytest.pl
body: <pre><code>#!/usr/bin/perl
  use strict;
  use warnings;
  use List::Util qw(min max);
  use Set::IntervalTree;
  use GenomeLookupUtil;
  
  my $chromCol = 0;
  my $startCol = 0;
  my $endCol   = 0;
  if($ARGV[2] eq "VSC") {
      $chromCol = 0;
      $startCol = 1;
      $endCol   = 2;
  } else {
      $chromCol = 1;
      $startCol = 2;
      $endCol   = 3;
  }
  
  open (IN2,"$ARGV[0]") || die "counldn't open";
  print STDERR "Read mask file \n";
  my @masklines   = ();
  my $i           = 0;
  my %mask_hash   = ();
  my $current_chr = '01';
  my $current_snp_ranges = Set::IntervalTree-&gt;new();
  while (&lt;IN2&gt;){
      my @masklines = split ("\t", $_);
      if ($masklines[1] ne $current_chr) {
              $mask_hash{$current_chr} = $current_snp_ranges;
              $current_snp_ranges = Set::IntervalTree-&gt;new();
      }
  
      $current_chr = $masklines[$chromCol];
      $current_snp_ranges-&gt;insert(
          [ $masklines[$startCol], $masklines[$endCol] ],
            $masklines[$startCol], 
            $masklines[$endCol]
      );
  }
  $mask_hash{$current_chr} = $current_snp_ranges;
  close (IN2);
  </code></pre>
  
  <p>When I am running code with unnecessary arguments which is a file its showing error as </p>
  
  <pre><code>Use of uninitialized value in subroutine entry at mytest.pl line 47, &lt;IN2&gt; line 100.
  </code></pre>
  
  <p>I have initialized all the variable and top of that I am not using any subroutine also in my code. Line 47 is </p>
  
  <pre><code>$current_snp_ranges-&gt;insert(
        [ $masklines[$startCol], $masklines[$endCol] ],
          $masklines[$startCol], 
          $masklines[$endCol]
  );
  </code></pre>