[bug]: `lncli closechannel` accepts a negative `sat_per_vbyte` value

[ZZiigguurraatt]

lncli closechannel accepts a negative sat_per_vbyte, for example

132cfa64874d:/$ lncli closechannel --sat_per_vbyte=-1 --chan_point 21a58fdfc744d209cb36aefe8e3ee5ae6471d0924dbf0dbef122bff3f3c93f1e:0
Channel close successfully initiated
Channel close transaction broadcasted: 3c7ea0661bcfb802a348a381e61b13e6aada5cfcfc1fce6c27a47ed6393bf0a9
{
    "closing_txid": "3c7ea0661bcfb802a348a381e61b13e6aada5cfcfc1fce6c27a47ed6393bf0a9"
}
132cfa64874d:/$ 

however, if I try to do it with the raw gRPC, I get

$ close_test --sat_per_vbyte -1 --channel_point 21a58fdfc744d209cb36aefe8e3ee5ae6471d0924dbf0dbef122bff3f3c93f1e:0

=============================

unknown exception
Value out of range: -1
Traceback (most recent call last):
  File "/mini_META/scripts/close_test", line 19, in <module>
    for response in litd_node_objects['bob']['lnd'].close_channel(channel_point=arguments.channel_point, sat_per_vbyte=arguments.sat_per_vbyte, no_wait=True):
  File "/usr/local/lib/python3.10/dist-packages/lndgrpc/errors.py", line 65, in wrapper
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/lndgrpc/errors.py", line 26, in wrapper
    return fnc(*args, **kwargs)
  File "/usr/local/lib/python3.10/dist-packages/lndgrpc/lightning.py", line 193, in close_channel
    request = lightning.CloseChannelRequest(
ValueError: Value out of range: -1

which makes sense.