Edge case in Combinator.choice/1

```
[info] ! Combinator.choice/1: Falsified after 90 passed tests.
[info] > ARG_0: "枇噻㷻讃"
[info] > ARG_1: ""
[info] > ARG_2: "\u0000"
[info] > ARG_2_ORIGINAL: "얐꽭ḋ廧뀎陏ၢ茁迏ἵ䝨쑥醹黜㱩隢ଧꜾ㹉᥂乬䙗⫑뼂ữ॥鈘䇏蠵ܺ漽탳蜥礵㓹䉔눎只睃绪㚱뽈ి蹈쌁쳪鶙ꝺ愛ꄒ늾ᶰ榉泆⑦캳蔅௯抡⦡喝ᥡ讔ᅄ벎ꎏ誹ᑁ涝寣㒿ɜ烞ə윕"
```