[Bug] [TeamSpen's Hammer Addons] Error model if copy and paste entities with helpers and sprites

[MyGamepedia]

Describe the bug TeamSpen's Hammer Addons uses model helper for sprite entities, this allows you to place them more accurately than with the white cube.

Copy and paste cause helper model to use value from model property, which sprites uses to display sprite texture. This cause helper model to use a non existing model and replace it with placeholder.

Fixes with Undo button somehow. Doesn't happen when you place sprite entity via Entity Tool or when you replace an entity with a sprite entity.

To Reproduce

1. Download TeamSpen's Hammer Addons.
2. Open H++.
3. Create env_sprite.
4. Duplicate it with ctrl+c and ctrl+v.
5. Error success.