This can also be used to track the status of a transaction, since result will be null until the transaction is mined. However, unlike
eth_getTransactionByHash which returns
null for unknown transactions, and a non-null response with 3
null fields for a pending transaction,
null for both pending and unknown transactions.
This call is also commonly used to get the contract address for a contract creation tx.
Note: the receipt is not available for pending transactions.