querying empty signal tally causes index panic

[cmwaters]

Found by using the following command on arabica:

❯ celestia-appd query signal tally 3 --node https://rpc.celestia-arabica-11.com:443
Error: rpc error: code = Unknown desc = runtime error: index out of range [7] with length 7: panic

[rootulp]

hmm, I can't repro with that exact command or a few variants of that command:

celestia-appd query signal tally 3 --node https://celestia-mainnet-rpc.itrocket.net:443
celestia-appd query signal tally 4 --node https://rpc.celestia-arabica-11.com:443
celestia-appd query signal tally 5 --node https://rpc.celestia-arabica-11.com:443

I think we'll need to write unit tests against the RPC / gRPC endpoint to try and repro

[rootulp]

I reproed this by running single-node.sh from #4041 and then ./scripts/upgrade-to-v3.sh

# Query during app version 1
$ celestia-appd query signal tally 3
Error: rpc error: code = Unknown desc = kv store with key KVStoreKey{0x14001209a90, signal} has not been registered in stores: panic

# Query during app version 2
$ celestia-appd query signal tally 3
threshold_power: "4167"
total_voting_power: "5000"
voting_power: "0"

# Query after validator signals for v3
$ celestia-appd query signal tally 3
threshold_power: "4167"
total_voting_power: "5000"
voting_power: "5000"

# Query after the try upgrade but before v3 activation height
$ celestia-appd query signal tally 3
Error: rpc error: code = Unknown desc = runtime error: index out of range [7] with length 6: panic

[rootulp]

The upgrade key is getting iterated over when calculating the tally. I added a unit test and fix.