819. Assignment of right to sue.

A bare equity to rescind a contract on the ground of misrepresentation is not assignable nor saleable1; but where property or an interest in property is assigned, there passes with it every such equity as is incidental to its effectual enjoyment, or necessary to secure it for the benefit of the assignee, including the equity of avoiding, or obtaining a court order to avoid, any conveyance or contract which stands in the way of such enjoyment, or destroys or prejudices such interest