message: dont invoke methods that dont exist on contract
diff: @@ -176,7 +176,7 @@ module.exports = class EthereumClient {
  async callContractMethod(contract, methodName, arg) {
  let result;
  - if (!contract || !methodName) { return; }
  + if (!contract || !methodName || typeof contract.methods[methodName] !== 'function') { return; }
  try {
  result = arg == null ? await contract.methods[methodName]().call() :
  