fix #39948, stack overflow due to free typevar during jl_type_intersection2
#39959
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I don't have a complete fix for this, but it seems type intersection sometimes returns a type with free variables, throwing a wrench into the works. The temporary solution is to try not to pass an intersection result back into intersection. In such a case I doubt jl_type_intersection2 could have been doing anything useful anyway, so it seems safe to just disable part of it when that happens.