Problem
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Console.systemOut is hooked up to Terminal.get, which internally calls
ProxyTerminal, which lets us deffer the wiring of terminal to
activeTerminal. This mechanism allows us to swap out the terminal
capable of standard out forwarding for sbtn.
However, as it stands this breaks the contract of being able to use
Console.systemOut with wrapped inside of `Terminal.withStreams() {...}`.

Solution
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Check if `activeTerminal.get` returns `null`, and if so initialize it to
the conventional `Terminal.SimpleTerminal`, which behaves as expected.