Events websocket

return new Promise((_, rej) => {
    const provider = webSocketProvider()
    //@ts-ignore
    provider.on('error', e => rej(e))

    const web3 = new Web3(provider)

    try {
      var contract = new web3.eth.Contract(signaturesAbi, SIGNATURES_CONTRACT)
      contract.events
        .NewMigration({ fromBlock: verifiedSignatureLatestBlock }, handleEvent)
        .on('error', (event: any) => debug.error(event, 'error on signature event'))
    } catch (error) {
      rej(error)
    }
  })

the webSocketProvider function is missing

export function webSocketProvider() {
  return new Web3.providers.WebsocketProvider(WEB3_WEBSOCKET_PROVIDER!, {
    timeout: 5000,

    clientConfig: {
      //ping to keep the connection alive
      keepalive: true,
      keepaliveInterval: 5000, // ms

      //ping timeout in case of connection problems
      dropConnectionOnKeepaliveTimeout: true,
      keepaliveGracePeriod: 5000, // ms
    },

    //try to connect again
    reconnect: {
      auto: true,
      delay: 5000, // ms
      maxAttempts: 5,
      onTimeout: false,
    },
  })
}