common: use a default chain name in fromGethGenesis if no chain name specified (#2319)

* common: make chain name mandatory in fromGethGenesis

* improve comment

* change startegy to just pass name custom

* undo comment

Author: g11tech

packages/common/src/common.ts

@@ -166,7 +166,7 @@ export class Common extends EventEmitter {
   ): Common {
     const genesisParams = parseGethGenesis(genesisJson, chain)
     const common = new Common({
-      chain: genesisParams.name,
+      chain: genesisParams.name ?? 'custom',
       customChains: [genesisParams],
       hardfork,
     })