backend_manager can return 1 from tail call, so check negative value

[hzxuzhonghu]

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What this PR does / why we need it:

Which issue(s) this PR fixes: Fix https://github.com/kmesh-net/kmesh/issues/355

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Does this PR introduce a user-facing change?:

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[hzxuzhonghu]

Wa are not sure how the 1 was returned, and could not reproduce with latest code

[hzxuzhonghu]

didnot see again, this was likely to be caused by invalid mem access