Providing initial value to arg causes concretization

[moralismercatus]

With the new code selection, when preload assigns the given initial value after making it symbolic, it is inadvertently concretized.

The solution is to assign initial input via vm-node. Similar to how initial input is assigned for files.

[moralismercatus]

It appears that I needed only to remove an assignment done in preloader that was done for historical reasons.