fix: topK and topP not valid

[wenyangchou]

The code is not valid

del_all(logits_warpers)
del_all(logits_processors)

for generate function is used yield as a return. As a result , generate has not been finished yet, and the wrapper has beed deleted.

[wenyangchou]

When I deleted the code , there is a significant decrease in the number of bad cases .

[fumiama]

Thanks! That's a severe problem.

[fumiama]

ref #543

[AdamMayor2018]

这个解决不了出现unexpected end at index [0]和显存爆炸问题。

[fumiama]

这个解决不了出现unexpected end at index [0]和显存爆炸问题。

unexpected end at index [0] 本身就和输入的内容和各项参数有关，但是这个错误大大加重了此问题。