- Fixed a minor bug for array autovivification on slice creation.

Example:
	var x = [];
	x[4,5] = [1,2];		# slice autovivification
	say x.map {"test"};	# works correctly now
	say x;			# prints: [nil, nil, nil, nil, 1, 2]

lib/Sidef/Exec.pm

@@ -134,7 +134,7 @@ package Sidef::Exec {
                             }
 
                             foreach my $ind ($#{$self_obj} + 1 .. $num) {
-                                $self_obj->[$num] //= Sidef::Variable::Variable->new(name => '', type => 'var');
+                                $self_obj->[$ind] //= Sidef::Variable::Variable->new(name => '', type => 'var');
                             }
 
                             $ind = $num;