Finch crash/panic with sysbench example

[srikiraju]

I run into this executing benchmarks/sysbench/setup.yaml. Problem seems to be introduced by one of the recent commits.

2024/02/09 08:42:58.619585 DEBUG workload.go:204 1(setup)/e2(dml1)/g1/c1
2024/02/09 08:42:58.619638 DEBUG workload.go:225 --- 1(setup)/e2(dml1)/g1/c1/t1(insert-rows.sql)/q1
panic: invalid scope: row

goroutine 1 [running]:
github.com/square/finch/data.NewScopedGenerator({{0x1, {0xc0000b0ec0, 0x5}, 0x2, {0xc0003a4204, 0x4}, 0x1, 0x1, 0x1, {0xc0000c2274, ...}, ...}, ...}, ...)
        /home/ec2-user/finch/data/scope.go:184 +0x31c
github.com/square/finch/data.(*Scope).Copy(0xc0001482d0, {0xc0002b4022, 0x2}, {0x1, {0xc0000b0ec0, 0x5}, 0x2, {0xc0003a4204, 0x4}, 0x1, ...})
        /home/ec2-user/finch/data/scope.go:119 +0x578
github.com/square/finch/workload.(*Allocator).Clients(0xc0000fd2f0, {0xc000092d20?, 0x3, 0x0?}, 0x0)
        /home/ec2-user/finch/workload/workload.go:231 +0x19e5
github.com/square/finch/stage.(*Stage).Prepare(0xc000112800, {0x1?, 0x7e5d00?})
        /home/ec2-user/finch/stage/stage.go:94 +0x4f8
github.com/square/finch/compute.(*Server).run(_, {_, _}, {{0x0, {0x8776c8, 0x1}}, 0x0, {0xc0000ca680, 0x33}, {0x0, ...}, ...})
        /home/ec2-user/finch/compute/server.go:111 +0x5da
github.com/square/finch/compute.(*Server).Run(0x7e4dee?, {0x87d920, 0xc000094870}, {0xc00013e1e0?, 0x1, 0x0?})
        /home/ec2-user/finch/compute/server.go:57 +0x131
github.com/square/finch/boot.Up({{0xc000094050, 0x5, 0x5}, {0xc000116280, 0x25, 0x25}})
        /home/ec2-user/finch/boot/boot.go:113 +0x505
main.main()
        /home/ec2-user/finch/bin/finch/main.go:12 +0x29