Issue: Detect and warn if RPC does not support archival history #505
Description
The README warns that “some L2s may not expose deep history unless using their archival RPC.”
GitHub
But the tool currently does not detect or warn when the RPC returns an error (e.g. block not found).
Improvement:
- On failure of w3.eth.get_block(block_A) or block_B, catch the error / returned None, and print a clear warning like: “block X not found — your RPC endpoint may not support archival history.”
- Exit with a distinct exit code (or include in JSON) so that users can programmatically detect it.
Benefits:
- Users get clearer diagnostics.
- Avoid confusing “value changed” vs “data missing / unreachable block.”