Init command panics if genesis has empty config

[calbera]

Upstream minor bug - genesis.IsVerkle() call panics with nil pointer deref if the genesis config doesn't contain a config field, even though the config field is not explicitly required.

bera-geth/cmd/bera-geth/chaincmd.go

Line 295 in 74b165a

triedb = utils.MakeTrieDatabase(ctx, chaindb, ctx.Bool(utils.CachePreimagesFlag.Name), false, genesis.IsVerkle())

Some execution spec tests fail because they don't have the config section filled out in the genesis.json.

Failing on geth upstream v1.16.2 so not a bera-geth specific issue.