Handle the case when nodes with overriding start on the fresh network (…

…#2106)

## Checklist
- [x] New behavior is reflected in tests

### Before requesting review
- [x] I have reviewed the code myself

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 
+- [2106](https://github.com/FuelLabs/fuel-core/pull/2106): Handle the case when nodes with overriding start on the fresh network.
 - [2105](https://github.com/FuelLabs/fuel-core/pull/2105): Fixed the rollback functionality to work with empty gas price database.
 
 ## [Version 0.33.0]

crates/fuel-core/src/database.rs

@@ -126,10 +126,14 @@ pub type ReyalerIterableKeyValueView = IterableKeyValueView<ColumnType<Relayer>>
 pub type GenesisDatabase<Description = OnChain> = Database<Description, GenesisStage>;
 
 impl OnChainIterableKeyValueView {
-    pub fn latest_height(&self) -> StorageResult<BlockHeight> {
+    pub fn maybe_latest_height(&self) -> StorageResult<Option<BlockHeight>> {
         self.iter_all_keys::<FuelBlocks>(Some(IterDirection::Reverse))
             .next()
-            .ok_or(not_found!("BlockHeight"))?
+            .transpose()
+    }
+
+    pub fn latest_height(&self) -> StorageResult<BlockHeight> {
+        self.maybe_latest_height()?.ok_or(not_found!("BlockHeight"))
     }
 
     pub fn latest_block(&self) -> StorageResult<CompressedBlock> {

crates/fuel-core/src/service.rs

@@ -227,7 +227,11 @@ impl FuelService {
                 let on_chain_view = combined_database.on_chain().latest_view()?;
 
                 for override_height in poa.get_all_overrides().keys() {
-                    let current_height = on_chain_view.latest_height()?;
+                    let Some(current_height) = on_chain_view.maybe_latest_height()?
+                    else {
+                        // Database is empty, nothing to rollback
+                        return Ok(());
+                    };
 
                     if override_height > &current_height {
                         return Ok(());

tests/tests/regenesis.rs

@@ -693,6 +693,47 @@ async fn starting_node_with_overwritten_old_poa_key_doesnt_rollback_the_state(
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread")]
+async fn starting_empty_node_with_overwritten_poa_works() -> anyhow::Result<()> {
+    let mut rng = StdRng::seed_from_u64(1234);
+    let state_config = StateConfig::local_testnet();
+    let mut original_chain_config = ChainConfig::local_testnet();
+    let tmp_dir = tempdir()?;
+    let tmp_path: PathBuf = tmp_dir.path().into();
+    let snapshot_writer = SnapshotWriter::json(tmp_path.clone());
+
+    // Given
+    let (original_secret_key, original_address) = random_key(&mut rng);
+    original_chain_config.consensus =
+        ConsensusConfig::PoAV2(PoAV2::new(original_address, {
+            let mut overrides = BTreeMap::default();
+            overrides.insert(123.into(), original_address);
+            overrides
+        }));
+    snapshot_writer.write_state_config(state_config.clone(), &original_chain_config)?;
+
+    // When
+    let result = FuelCoreDriver::spawn_with_directory(
+        tmp_dir,
+        &[
+            "--debug",
+            "--poa-instant",
+            "true",
+            "--snapshot",
+            tmp_path.to_str().unwrap(),
+            "--consensus-key",
+            original_secret_key.to_string().as_str(),
+        ],
+    )
+    .await;
+
+    // Then
+    let core = result.expect("Failed to start the node");
+    produce_block_with_tx(&mut rng, &core.client).await;
+
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn starting_node_with_overwritten_new_poa_key_rollbacks_the_state(
 ) -> anyhow::Result<()> {