add CHANGELOG entry

CHANGELOG.md

@@ -55,6 +55,7 @@
 - [#2014](https://github.com/poanetwork/blockscout/pull/2014) - fix: use better queries for listLogs endpoint
 - [#2027](https://github.com/poanetwork/blockscout/pull/2027) - fix: `BlocksTransactionsMismatch` ignoring blocks without transactions
 - [#2070](https://github.com/poanetwork/blockscout/pull/2070) - reduce `max_concurrency` of `BlocksTransactionsMismatch` fetcher
+- [#2083](https://github.com/poanetwork/blockscout/pull/2083) - allow total_difficuly to be nil
 
 ### Chore
 

apps/ethereum_jsonrpc/lib/ethereum_jsonrpc/block.ex

@@ -439,7 +439,7 @@ defmodule EthereumJSONRPC.Block do
     {key, quantity_to_integer(quantity)}
   end
 
-  # Size may be `nil` for uncle blocks
+  # Size and totalDifficulty may be `nil` for uncle blocks
   defp entry_to_elixir({key, nil}) when key in ~w(size totalDifficulty) do
     {key, nil}
   end