Segfault using --vsp.sync

[isuldor]

dcrwallet linux-amd64-v1.6.0-rc3 segfaults when attempting to use the --vsp.sync flag:

$ dcrwallet --promptpass --vsp.sync
2020-11-16 10:08:06.632 [INF] DCRW: Version 1.6.0-rc3+release (Go version go1.15.5 linux/amd64)
2020-11-16 10:08:07.898 [INF] WLLT: Opened wallet
Enter private passphrase:
2020-11-16 10:08:18.199 [INF] WLLT: The wallet has been unlocked without a time limit
2020-11-16 10:08:18.199 [INF] DCRW: Starting auto transaction creator
2020-11-16 10:08:18.200 [INF] RPCS: Listening on 127.0.0.1:9110
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xb78e37]

goroutine 26 [running]:
decred.org/dcrwallet/internal/vsp.(*VSP).Sync(0x0, 0x10c6060, 0xc000304900)
        decred.org/dcrwallet@v1.6.0-rc3/internal/vsp/vsp.go:280 +0x37
created by main.run.func14
        decred.org/dcrwallet@v1.6.0-rc3/dcrwallet.go:419 +0xba

Seems like this feature would be useful given that vspd can require several fee payment attempts to pick up a new ticket. I'm assuming that's the intention of this flag, as afaik there is no other way to check if my tickets are on the vsp.

dcrwallet --help
Usage:
...
VSP Options:
      --vsp.url=                               Base URL of the VSP server
      --vsp.pubkey=                            VSP server pubkey
      --vsp.sync                               sync tickets to vsp
...

[jrick]

Does this panic if both --enableticketbuyer and --vsp.url are configured?

[isuldor]

Sweet, the segfault is avoided with --enableticketbuyer configured. This makes sense in hindsight as ticketbuyer is talking to the vsp, so its plausible that I'm just misusing the flag without ticketbuyer enabled. Now I can set a high --ticketbuyer.balancetomaintainabsolute to avoid actually buying tickets.

I think all we may need here is a warning message indicating "ticketbuyer is not enabled, will not sync tickets to vsp."

[xaur]

Getting a similar segfault with dcrwallet v1.6.3. I would like to sync managed tickets even when the ticketbuyer is off like suggested by #2058.