fix: handle edgecase where indexer hangs when a block has 0 transactions

[seanmcgary]

Description

Bug fix for a situation observed on holesky where the indexer would hang when trying to batch fetch 0 transactions. This was only found when using a direct node rather than a service like quiknode since we typically dont use the native batch call structure with quiknode.

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Unit test suite and manually running the sidecar to sync against the block that had 0 transactions on holesky.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings