Recursion while `onExpanderChange`

[Ahornberg]

Maybe @DaveVenom had a similar problem here:

VCV API module deletion / onExpanderChange() bug and work around - resolved

The following describes a bug that exists within the VCV API as of VCV Rack version 2.4.1. Every rack module maintains a pair of Module::Expander objects, one for the left neighbor, and one for the right. Among other things, each Expander object has a module* pointer to the neighbor module, as well as the moduleId of the neighbor. If there is no neighbor, then the module* = NULL, and the moduleId = -1. The Module::onExpanderChange() event handler is supposed to be called whenever a neighbor is…