[BUG] Errors with erigon nodes

[engn33r]

Describe the bug
Using a public RPC that's running erigon, not geth, results in errors.

To Reproduce
Steps to reproduce the behavior:

1. Run sothis with an RPC using erigon using this list. For example sothis --mode fast_track --source_rpc https://eth-mainnet.public.blastapi.io --contract_address 0xbebc44782c7db0a1a60cb6fe97d0b483032ff1c7 --storage_slot 80084422859880547211683076133703299733277748156566366325829078699459944778999 --origin_block 16870000 --terminal_block 16910000 --query_interval 100 --filename tripool_usdc.json
2. Observe an error such as Error: RequestFailed("\"finding bebc44782c7db0a1a60cb6fe97d0b483032ff1c7 in the changeset 17939419: account changes purged for block 17939419\"")
   Using the RPC https://rpc.builder0x69.io instead returns the error Error: JsonDeserializationFailed("error decoding response body: expected value at line 1 column 1")

Note: blutgang does not give an error in most of these cases, only sothis encounters an error.

Expected behavior
No errors. Or consider checking what server software is running and returning an error to the user if the result is not geth.