Email alert when blob missing from CL

[syntrust]

Fixes #480.

Reproduced by creating a new mainnet es-node and downloading blocks using --download.start 23935930 and --l1.beacon http://65.21.133.53:4200, as the blob at 23935934 was missing in 65.21.133.53.

ERROR[12-04|09:55:02.715] Did not find the event specified blob in the CL

This fix has been verified in the same environment with and without email configured.

Email example:

The downloader couldn't locate the specified blob in the consensus layer. The node is stopped pending resolution. Details from the EL event:
 - blockNumber: 23935934
 - kvIndex: 274
 - hash: 0x017d51be97d12e36e191e68f9873d0eccf89e7250a66eb2fe41b58cb14c761a2
This may indicate a potential issue with blob availability on the consensus layer.


Sent at: Fri, 05 Dec 2025 04:33:58 +0100

[qzhodl]

How did you test it and what is the test result?

[syntrust]

How did you test it and what is the test result?

Mock an error in func (c *BeaconClient) DownloadBlobs(slot uint64) (map[common.Hash]Blob, error) and you will receive an email (if configured) or crash with a log, e.g.,

ERROR[12-31|19:06:22.404] Failed to download blobs for the block after 3 attempts block=9,951,215 err="no beacon client or DA client is available"
ERROR[12-31|19:06:22.404] "🛑 Fatal Error from es-node: Downloader Failed to Locate Blob in CL"
CRIT [12-31|19:06:22.404] The downloader couldn't locate the specified blob in the consensus layer. The node is stopped pending resolution. Details from the EL event: 
 - blockNumber: 9951215
 - kvIndex: 176
 - hash: 0x013359b2afa290546c48b2a5c4998cb60aba11a273527eb92232a0df2a08bc83
This may indicate a potential issue with blob availability on the consensus layer. 

[qzhodl]

How did you test it and what is the test result?

Mock an error in func (c *BeaconClient) DownloadBlobs(slot uint64) (map[common.Hash]Blob, error) and you will receive an email (if configured) or crash with a log, e.g.,

ERROR[12-31|19:06:22.404] Failed to download blobs for the block after 3 attempts block=9,951,215 err="no beacon client or DA client is available"
ERROR[12-31|19:06:22.404] "🛑 Fatal Error from es-node: Downloader Failed to Locate Blob in CL"
CRIT [12-31|19:06:22.404] The downloader couldn't locate the specified blob in the consensus layer. The node is stopped pending resolution. Details from the EL event: 
 - blockNumber: 9951215
 - kvIndex: 176
 - hash: 0x013359b2afa290546c48b2a5c4998cb60aba11a273527eb92232a0df2a08bc83
This may indicate a potential issue with blob availability on the consensus layer. 

How to mock the error? Can I reproduce this error on my side?