fix: placeholder block hash when in forked mode

crates/katana/core/src/backend/mod.rs

@@ -3,7 +3,8 @@ use std::sync::Arc;
 use gas_oracle::L1GasOracle;
 use katana_executor::{ExecutionOutput, ExecutionResult, ExecutorFactory};
 use katana_primitives::block::{
-    BlockNumber, FinalityStatus, Header, PartialHeader, SealedBlock, SealedBlockWithStatus,
+    BlockHash, BlockNumber, FinalityStatus, Header, PartialHeader, SealedBlock,
+    SealedBlockWithStatus,
 };
 use katana_primitives::chain_spec::ChainSpec;
 use katana_primitives::da::L1DataAvailabilityMode;
@@ -110,11 +111,16 @@ impl<EF: ExecutorFactory> Backend<EF> {
 
         if block_number >= STORED_BLOCK_HASH_BUFFER {
             let block_number = block_number - STORED_BLOCK_HASH_BUFFER;
-            let block_hash = self
-                .blockchain
-                .provider()
-                .block_hash_by_num(block_number)?
-                .expect("qed; missing block hash");
+            let block_hash = self.blockchain.provider().block_hash_by_num(block_number)?;
+
+            // When in forked mode, we might not have the older block hash in the database. This
+            // could be the case where the `block_number - STORED_BLOCK_HASH_BUFFER` is
+            // earlier than the forked block, which right now, Katana doesn't
+            // yet have the ability to fetch older blocks on the database level. So, we default to
+            // `BlockHash::ZERO` in this case.
+            //
+            // TODO: Fix quick!
+            let block_hash = block_hash.unwrap_or(BlockHash::ZERO);
 
             let storages = state_updates.storage_updates.entry(address!("0x1")).or_default();
             storages.insert(block_number.into(), block_hash);