fix CR comment

apps/block_scout_web/lib/block_scout_web/controllers/address_read_contract_controller.ex

@@ -26,8 +26,8 @@ defmodule BlockScoutWeb.AddressReadContractController do
     ]
 
     with {:ok, address_hash} <- Chain.string_to_address_hash(address_hash_string),
-         {:ok, address} <- Chain.find_contract_address(address_hash, address_options, true) do
-      if address.smart_contract do
+         {:ok, address} <- Chain.find_contract_address(address_hash, address_options, true),
+         false <- is_nil(address.smart_contract) do
       {transaction_count, validation_count} = transaction_and_validation_count(address_hash)
 
       render(
@@ -40,13 +40,7 @@ defmodule BlockScoutWeb.AddressReadContractController do
         validation_count: validation_count
       )
     else
-        not_found(conn)
-      end
-    else
-      :error ->
-        not_found(conn)
-
-      {:error, :not_found} ->
+      _ ->
         not_found(conn)
     end
   end