Error when generic circuit is set to Layout shape

[kendfrey]

Steps to reproduce

• Create a generic circuit (see generic-layout-bug.zip)
• Set the circuit's shape to Layout
• Try to embed the circuit in another circuit

Expected behaviour

The component renders with the "layout" shape.

Actual behaviour

The component generates an error something like:

Shape generic-layout-bug.dig is missing
Error in the evaluation of the generic code of the circuit. Code this.Bits = args.bits;
Value 'bits' is not available in the struct!; line 1