ERROR[05-11|08:36:53.373] RPC method dag_validateSpines crashed: runtime error: invalid memory address or nil pointer dereference
goroutine 21023 [running]:
gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*callback).call.func1()
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/service.go:200 +0x89
panic({0x1255a60, 0x2145530})
	runtime/panic.go:1038 +0x215
gitlab.waterfall.network/waterfall/protocol/gwat/core/types.(*Header).Nr(...)
	gitlab.waterfall.network/waterfall/protocol/gwat/core/types/block.go:166
gitlab.waterfall.network/waterfall/protocol/gwat/dag/finalizer.(*Finalizer).IsValidSequenceOfSpines(0xc0003ee930, {0xc00a0b6ea0, 0xc, 0xd})
	gitlab.waterfall.network/waterfall/protocol/gwat/dag/finalizer/finalizer.go:251 +0x365
gitlab.waterfall.network/waterfall/protocol/gwat/dag.(*Dag).HandleValidateSpines(0xc0001495e0, {0xc00a0b6ea0, 0xc, 0xd})
	gitlab.waterfall.network/waterfall/protocol/gwat/dag/dag.go:476 +0x1c6
gitlab.waterfall.network/waterfall/protocol/gwat/internal/ethapi.(*PublicDagAPI).ValidateSpines(0xc000bd4a00, {0xc019a448e0, 0xc0000a6c00}, {0xc00a0b6ea0, 0xc, 0xd})
	gitlab.waterfall.network/waterfall/protocol/gwat/internal/ethapi/api.go:2257 +0x45
reflect.Value.call({0xc0005a0d80, 0xc0005589b8, 0x7f949d6935b8}, {0x1400d64, 0x4}, {0xc0018500f0, 0x3, 0xc008cd43c0})
	reflect/value.go:543 +0x814
reflect.Value.Call({0xc0005a0d80, 0xc0005589b8, 0x56d0a8}, {0xc0018500f0, 0x3, 0x3})
	reflect/value.go:339 +0xc5
gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*callback).call(0xc0005cd3e0, {0x166d778, 0xc000bd4a00}, {0xc001a688e8, 0x12}, {0xc01afd0cc0, 0x1, 0x4dbc17})
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/service.go:206 +0x405
gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*handler).runMethod(0xc00a0d1c00, {0x166d778, 0xc000bd4a00}, 0xc01972c8c0, 0x0, {0xc01afd0cc0, 0x8, 0x164b980})
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/handler.go:388 +0x45
gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*handler).handleCall(0xc00017aa20, 0xc0020f62d0, 0xc01972c8c0)
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/handler.go:336 +0x239
gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*handler).handleCallMsg(0xc00017aa20, 0xc000102c00, 0xc01972c8c0)
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/handler.go:297 +0xd1
gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*handler).handleMsg.func1(0xc0020f62d0)
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/handler.go:138 +0x35
gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*handler).startCallProc.func1()
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/handler.go:225 +0xc8
created by gitlab.waterfall.network/waterfall/protocol/gwat/rpc.(*handler).startCallProc
	gitlab.waterfall.network/waterfall/protocol/gwat/rpc/handler.go:221 +0x92