How to replace $lb elements with empty elements

I have a list

set list=$lb(1,$c(0),2)

How do I replace $c(0) with an empty element?

My list should look like this:

set list=$lb(1,,2)

I tried using $list but it either replaces the element with an empty string:

set $list(list,2)=""
zw list

Resulting in:

list=$lb(1,"",2)

Or removes the element altogether:

set $list(list,2,2)=""
zw list

Resulting in:

list=$lb(1,2)