validatorRelayer daemon stalled with no error

[juehai]

run-command: yarn validatorRelayer $ETH_NETWORK

The daemon was stalled and stopped printing new blocknumber like 1641852906 At blocknumber: 10937741 {}.

Could we add a try/catch for below functions, it seems that the logger printed At blocknumber and then hang forever.

Two potential calling functions caused this:

1. await api.rpc.chain.subscribeFinalizedHeads failed, and did not catch the error
2. await api.query.system.events.at(blockHash); failed, and did not catch the error

    await api.rpc.chain
        .subscribeFinalizedHeads(async (head) => {
            const blockNumber = head.number.toNumber();
            logger.info(`At blocknumber: ${blockNumber}`);

            const blockHash = head.hash.toString();
            const events = await api.query.system.events.at(blockHash);
            events.map(async ({event}) => {
                const { section, method, data } = event;
                if (section === 'ethBridge' && method === 'AuthoritySetChange') {
                    const dataFetched = data.toHuman();
                    const eventIdFound = dataFetched[0];
                    const newValidatorSetId = parseInt(dataFetched[1]);
                    logger.info(`IMP Event found at block ${blockNumber} hash ${blockHash} event id ${eventIdFound}`);
                    await getEventPoofAndSubmit(api, eventIdFound, bridge, wallet, newValidatorSetId.toString(), blockHash, infuraProvider);
                }
            })
        });