Handle errors

[jiguantong]

API error

Any http error, including parameter errors, API unreachable errors, etc.
Allow error reporting. When the threshold error is reached, do not aggregate and directly publish the error.

Insufficient gas when publishing

ringecosystem/xapi-offchain#10
When the left gas may be insufficient, mark the request and try to publish it. When publishing it next time, publish an error message with very little gas. (Deprecated, because remark will be reverted when gas is insufficient)

Set the report limit size? If the limit is exceeded, reporter node can report error, treated as an API error 👆

Error callback?

Callback method for error?

try_aggregator_external?

Allow anyone to call try_aggregator?