TypeError: hex is not a function
at Function.from (native)
at Function.from (native)
at Object.<anonymous> (/root/ipfs-pubsub-room-demo/node_modules/ethereumjs-block/node_modules/ethereumjs-util/index.js:31:28)
at Module._compile (module.js:410:26)
at Object.Module._extensions..js (module.js:417:10)
at Module.load (module.js:344:32)
at Function.Module._load (module.js:301:12)
at Module.require (module.js:354:17)
at require (internal/module.js:12:17)
at Object.<anonymous> (/root/ipfs-pubsub-room-demo/node_modules/ethereumjs-block/header.js:1:77)