`elsif`

     55          if ($ct_scanout ) {
     ...          
     69          } elsif ($ct_scanout==0) {
     ...
     79          }

Here the answer is 'that can never happen'
But it's for a logical reason, not an application-specific reason
If neither case is true, it's because the universe is broken
If the first test fails, the second test is always true

        if ($ct_scanout) {
        ...
        } else {
        ...
        }