FSMP NPE overflow 问题

/cc @Berrysoft

发现了 7881 run 中 2370_1 也存在 NPE overflow：

./fsmp.py sparsify/0/7881/2370_1.h5 -o fsmp/0/7881/2370_1.pq --ref SER/0.h5 --vram 40 --full PE/0/7881/2370_1.pq
Analyze waveforms, 14306 in total.
Part 0 | 0:13684 with lengths of PE t 61, waveform 123 and NPE 15
Starting batch loop...
/mnt/stage/liuyq/commission/FSMP/analysis/fsmp/batch.py:213: RuntimeWarning:
                NPE overflow at step 3765:
                [(79336815148, 7111, 924, 8, 15, 76, 6.622469)]
                [('eid', '<u8'), ('ch', '<u2'), ('offset', '<u2'), ('s0', '<u2'), ('l_t', '<u4'), ('l_wave', '<u4'), ('sig2w', '<f4')]

我等这两个 run 跑完，汇总 Warning 后关 issue 吧。