Panic in Reconciler

[patrick-ogrady]

Describe the bug

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x8dcb18]

goroutine 63 [running]:
github.com/coinbase/rosetta-sdk-go/reconciler.(*Reconciler).reconcileInactiveAccounts(0xc0073e2210, 0xbe28a0, 0xc005b5b080, 0x0, 0x0)
        /home/ec2-user/go/src/github.com/coinbase/rosetta-sdk-go/reconciler/reconciler.go:644 +0xe8
github.com/coinbase/rosetta-sdk-go/reconciler.(*Reconciler).Reconcile.func2(0xc008ff6768, 0x0)
        /home/ec2-user/go/src/github.com/coinbase/rosetta-sdk-go/reconciler/reconciler.go:707 +0x3f
golang.org/x/sync/errgroup.(*Group).Go.func1(0xc0063b2270, 0xc0067e5bc0)
        /home/ec2-user/go/src/golang.org/x/sync/errgroup/errgroup.go:57 +0x64
created by golang.org/x/sync/errgroup.(*Group).Go
        /home/ec2-user/go/src/golang.org/x/sync/errgroup/errgroup.go:54 +0x66

To Reproduce

1. Sync some blocks to a persistent datadir using rosetta-cli check
2. Halt syncing
3. Restart check from the previous datadir