Nicolas,
Adding #nextAvailable: hurts nothing, but changing #next: (and #next too) will break existing code. In VW, it is only #next that has the silent failure trap, and while Cincom was willing to consider a change, they ultimately declined to make it. I am convinced that Dolphin gets it right, but I would be surprised to see us adopt its behavior. I would be thrilled if we did so, but doubt it will happen. Failing such breaking changes, I need to create a way to have my code work, which is why I started adding my own methods.
Your pluggable exception/defaultAction idea is worth a shot. Some simple testing should show whether it can preserve current behavior and throw exceptions, respectively. I think I heard Stef as much as say he would support it if it does serve both masters. Stef?
As I said I would like to have a one page description of the problem, solution, pros and cons May be put it on the wiki Right now we are messy in terms of process for changes. I personnally always hated the VW behavior because we lost a lot of time with code trapping error. But I do not want to take decision on my emotion because I could be wrong. So do a one page proposal with problem, solution, pros and cons. Stef