LND stopped. I'm not sure if there's much to do about this or anything but it's certainly unexpected/undesired. I'm hoping the shutdown logs may help to fix an issue. Feel free to close this one if it's not helpful.

Version 0.4, on a Debian 4.9.20-grsec, 25G free RAM, Bitcoin Core RPC client version v0.15.99.0-9cf6393a4

2018-03-29 04:49:24.813 [INF] CRTR: Block 000000000000000000155720ac9c425fc94b9c6343e2da0a4bb43dbb735544e0 (height=515624) clo
sed 0 channels
2018-03-29 04:49:24.867 [INF] NTFN: New block: height=515624, sha=000000000000000000155720ac9c425fc94b9c6343e2da0a4bb43dbb7355
44e0
2018-03-29 04:49:24.867 [INF] UTXN: Attempting to graduate height=515624: num_kids=0, num_babies=0
2018-03-29 04:49:26.692 [INF] CRTR: Updated vertex data for node=0312c02755c6a3475f872be27e71fdb7703a61a25777401a26125e1c772c7e0f6a
2018-03-29 04:49:30.203 [INF] NTFN: Cancelling epoch notification, epoch_id=15092
2018-03-29 04:49:30.203 [INF] HSWC: ChannelLink(393a14959e5e974f2b1af08f50da837baf08a9cd47a78e1c8f91e50dbab8bf13:0) has exited
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x8e8ef7]

goroutine 118602734 [running]:
github.com/lightningnetwork/lnd/lnwallet.(*commitmentChain).tail(...)
/data/coin/ln/go/src/github.com/lightningnetwork/lnd/lnwallet/channel.go:1051
github.com/lightningnetwork/lnd/lnwallet.(*LightningChannel).ReceiveNewCommitment(0xc5bb1ed200, 0x95876f9c07166d0e, 0xf027ee841935e65a, 0xca69236234982f72, 0xea563ca1e51eebb5, 0x56846c853f5fe541, 0xf2b3242d3bd13a74, 0x514c87875ae5ef7b, 0xd600a49189a4583f, 0x0, ...)
/data/coin/ln/go/src/github.com/lightningnetwork/lnd/lnwallet/channel.go:3648 +0xb7
github.com/lightningnetwork/lnd/htlcswitch.(*channelLink).handleUpstreamMsg(0xc5e688a5a0, 0x15b93c0, 0xc4ba8da300)
/data/coin/ln/go/src/github.com/lightningnetwork/lnd/htlcswitch/link.go:1235 +0xf08
github.com/lightningnetwork/lnd/htlcswitch.(*channelLink).htlcManager(0xc5e688a5a0)
/data/coin/ln/go/src/github.com/lightningnetwork/lnd/htlcswitch/link.go:921 +0x90e
created by github.com/lightningnetwork/lnd/htlcswitch.(*channelLink).Start
/data/coin/ln/go/src/github.com/lightningnetwork/lnd/htlcswitch/link.go:391 +0x150