`server does not support the reflection API` when celestia-appd starts with broken config

[rootulp]

Context

@renaynay and @cristaloleg had a validator with a broken config (app.toml, config.toml)

Problem

The broken config resulted in this symptom:

$ grpcurl -plaintext -d '{"subspace": "gov", "key": "votingparams"}' 51.159.158.12:9090 cosmos.params.v1beta1.Query/Params
Error invoking method "cosmos.params.v1beta1.Query/Params": failed to query for service descriptor "cosmos.params.v1beta1.Query": server does not support the reflection API

Basically all GRPC queries to the server failed with something like: server does not support the reflection API.

Proposal

1. Get the broken configs from their validator so that we can repro the issue. I looked but couldn't find them on the Scaleway instance. cc: @cmwaters
2. When celestia-app starts up, if it can't register reflection on the GRPC server, panic with an error message stating that config is invalid instead of starting up.