raft.Snapshot() snapshots to 0 if there are no new log entries about raft HOT 4 CLOSED

So the problem seems to be in raft.runFSM(), the lastIndex & lastTerm variables are local to the func, are only set when there's a commit or a restore called for, but the initial load of the snapshot at startup is done outside of that via restoreSnapshot(). so if the first request that runFSM() sees is to create a snapshot, it hasn't set lastIndex & lastTerm yet.

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@superfell This is an interesting one. I'm not sure what the correct behavior is in this case. The snapshot really is capturing nothing if there is no commits or restores prior to this, so that part is correct. We should be calling restoreSnapshot() before returning the Raft instance, so I'm not even sure how this is possible.

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From what i could tell, the initial snapshot load at startup doesn't go through the FSM goroutine.

It seems like either it should spot this and return an error for the snapshot attempt (as there's nothing new that would require a snapshot), or the FSM goroutine should initialize it index/term local vars from the Raft instance. I'd be happy to code up either solution if you have a prefernce [i mostly lean towards having the snapshot attempt return an error]

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@superfell Agreed, it is strange to snapshot when there is no data. Lets go with the error return.

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