Add support for failed transactions

Do you want to request a feature or report a bug?
Feature

What is the current behavior?
Transactions do not support the status flag from receipts, nor do they support the error reason (gas or revert reason). Moreover only successful call transactions will invoke a subgraph's handlers.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.

What is the expected behavior?
That a failed transaction from an invocation of a call handler would:
a) Trigger the call handler in the subgraph
b) That the EthereumTransaction class would contain the following:
* a flag for status reflecting the success status of the transaction
* an errorType - reverted or out-of-gas (others?)
* the revertReason if any (which is easy to surface in ethers and web3)

The main motivation for something like this is for projects, such as ours, to track errors users have when interacting with our contracts (for monitoring tools). As users pay gas even for failed transactions, it's critical to minimize these where possible. It's even more important when they call our functions from their own contracts. As you can imagine, these calls are harder to track as unlike regular transactions invoking our contracts directly (where we are the to destination of the transaction) - their to destination is their contract which is calling ours by reference in the code.

Issue では EthereumTransaction クラスと subgraph の call handler が挙げられていますが、リポジトリのファイルやテストは示されていません。まず receipts と call handler がどのように処理されるかを追跡し、その後、失敗したトランザクションをどのように表現してディスパッチすべきかを判断してください。失敗した call が handler をトリガーし、status、error type、および存在する場合は revert reason を公開すれば完了です。