fix bug in scheduler.step(). Indices should be either on cpu or on th…

[LiaoFJ]

fix bug in scheduler.step(). Indices should be either on cpu or on the same device as the indexed tensor. (same as func add_noise())

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Fixes # (issue)

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@yiyixuxu

[hlky]

Hi @LiaoFJ. Can you share a reproduction?

[LiaoFJ]

Hi @LiaoFJ. Can you share a reproduction?

Somehow it works .. just ignore it