fix(l1): made the tx-spammer work with our node (#1027)

**Motivation**

Have the tx spammer running instead of immediatly shutting down when we
are the first node in the devnet setup.

**Description**

This PR tackled a couple of issues until we were able to process an
initial transaction, (they are small changes):
- We were returning an error on `eth_getTransactionCount` when we either
didn't have a `latest` block before genesis or at any point when we
don't have `pending` blocks. The solution in this case was returning
`0x0` in those cases.
- When requesting `eth_getTransactionCount` on `pending` after some
transaction went through we were defaulting to `0x0`, it appears that
the idea is to default to the `latest` in those case which make sense.
- There were a missing filter that made the node panic when building
payloads for transactions with fees lower than the base_fee_per_gas,
this generated that those kind of transactions stopped the node's
ability to build blocks when they were in the mempool, we made a quick
workaround in this PR, but will remove it in favor of #1018

Closes #1026

Author: rodrigo-o

crates/networking/rpc/eth/account.rs

@@ -156,9 +156,8 @@ impl RpcHandler for GetTransactionCountRequest {
         );
 
         let Some(block_number) = self.block.resolve_block_number(&storage)? else {
-            return Err(RpcErr::Internal(
-                "Could not resolve block number".to_owned(),
-            )); // Should we return Null here?
+            return serde_json::to_value("0x0")
+                .map_err(|error| RpcErr::Internal(error.to_string()));
         };
 
         let nonce = storage

crates/networking/rpc/types/block_identifier.rs

@@ -39,7 +39,15 @@ impl BlockIdentifier {
                 BlockTag::Finalized => storage.get_finalized_block_number(),
                 BlockTag::Safe => storage.get_safe_block_number(),
                 BlockTag::Latest => storage.get_latest_block_number(),
-                BlockTag::Pending => storage.get_pending_block_number(),
+                BlockTag::Pending => {
+                    storage
+                        .get_pending_block_number()
+                        // If there are no pending blocks, we return the latest block number
+                        .and_then(|pending_block_number| match pending_block_number {
+                            Some(block_number) => Ok(Some(block_number)),
+                            None => storage.get_latest_block_number(),
+                        })
+                }
             },
         }
     }

test_data/el-stability-check.yml

@@ -24,7 +24,7 @@ tasks:
 
 - name: run_task_matrix
   title: "Check block proposals from all client pairs"
-  timeout: 2m
+  timeout: 3m
   configVars:
     matrixValues: "validatorPairNames"
   config:

test_data/network_params.yaml

@@ -20,4 +20,6 @@ assertoor_params:
   run_block_proposal_check: false
   run_blob_transaction_test: true
   tests:
-    - 'https://raw.githubusercontent.com/lambdaclass/lambda_ethereum_rust/refs/heads/main/test_data/el-stability-check.yml'
+    - 'https://raw.githubusercontent.com/lambdaclass/lambda_ethereum_rust/refs/heads/main/test_data/el-stability-check.yml'
+tx_spammer_params:
+  tx_spammer_extra_args: ["--accounts=10", --txcount=10]