ToString of model with Parameters causes a stackoverflow

[sir-deenicus]

A basic model with parameters causes a stack overflow when printed to interactive.

I think this is related to fact that in ToString() there is:

for mm in m.descendants do

but descendants in turn has m :: [for child in m.children do yield! child.descendants], adding itself to descendants. Unsure why this seems to only occur for parameters, not buffers or models.

A simple m <> mm resolves the crash but I'm not sure if that's the correct action to take.