Inside your SimpleGraph{T} function, you have a call to SimpleGraph(...) with two arguments (specifically in complement(SimpleGraph(tnv, maxe - ne))), and that in turn calls SimpleGraph{T} again.
You could try changing it to complement(SimpleGraph{T}(tnv, maxe - ne)) (ie add a {T}, and maybe to the other call as well) so SimpleGraph{T} is only calling itself, which that post seems to suggest is better.