refactor: Move LoadGenesisBlock to ChainstateManager

diff --git a/src/node/blockstorage.cpp b/src/node/blockstorage.cpp
index 8726c741..8771c353 100644
--- a/src/node/blockstorage.cpp
+++ b/src/node/blockstorage.cpp
@@ -1305,7 +1305,7 @@ void ImportBlocks(ChainstateManager& chainman, std::span<const fs::path> import_
         chainman.m_blockman.m_blockfiles_indexed = true;
         LogInfo("Reindexing finished");
         // To avoid ending up in a situation without genesis block, re-try initializing (no-op if reindexing worked):
-        chainman.ActiveChainstate().LoadGenesisBlock();
+        (void)chainman.LoadGenesisBlock();
     }
 
     // -loadblock=
diff --git a/src/node/chainstate.cpp b/src/node/chainstate.cpp
index 1725fe70..c27447b7 100644
--- a/src/node/chainstate.cpp
+++ b/src/node/chainstate.cpp
@@ -62,7 +62,7 @@ static ChainstateLoadResult CompleteChainstateInitialization(
     // If we're not mid-reindex (based on disk + args), add a genesis block on disk
     // (otherwise we use the one already on disk).
     // This is called again in ImportBlocks after the reindex completes.
-    if (chainman.m_blockman.m_blockfiles_indexed && !chainman.ActiveChainstate().LoadGenesisBlock()) {
+    if (chainman.m_blockman.m_blockfiles_indexed && !chainman.LoadGenesisBlock()) {
         return {ChainstateLoadStatus::FAILURE, _("Error initializing block database")};
     }
 
diff --git a/src/test/util/chainstate.h b/src/test/util/chainstate.h
index 48a3381a..aeec14cc 100644
--- a/src/test/util/chainstate.h
+++ b/src/test/util/chainstate.h
@@ -80,7 +80,7 @@ CreateAndActivateUTXOSnapshot(
             node.chainman->ResetChainstates();
             node.chainman->InitializeChainstate(node.mempool.get());
             Chainstate& chain = node.chainman->ActiveChainstate();
-            Assert(chain.LoadGenesisBlock());
+            Assert(node.chainman->LoadGenesisBlock());
             // These cache values will be corrected shortly in `MaybeRebalanceCaches`.
             chain.InitCoinsDB(1_MiB, /*in_memory=*/true, /*should_wipe=*/false);
             chain.InitCoinsCache(1_MiB);
diff --git a/src/test/validation_chainstate_tests.cpp b/src/test/validation_chainstate_tests.cpp
index 141c67da..bcbb553d 100644
--- a/src/test/validation_chainstate_tests.cpp
+++ b/src/test/validation_chainstate_tests.cpp
@@ -43,7 +43,7 @@ BOOST_AUTO_TEST_CASE(validation_chainstate_resize_caches)
     c1.InitCoinsDB(
         /*cache_size_bytes=*/8_MiB, /*in_memory=*/true, /*should_wipe=*/false);
     WITH_LOCK(::cs_main, c1.InitCoinsCache(8_MiB));
-    BOOST_REQUIRE(c1.LoadGenesisBlock()); // Need at least one block loaded to be able to flush caches
+    BOOST_REQUIRE(manager.LoadGenesisBlock()); // Need at least one block loaded to be able to flush caches
 
     // Add a coin to the in-memory cache, upsize once, then downsize.
     {
diff --git a/src/validation.cpp b/src/validation.cpp
index 5341c604..8069f51b 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -4943,30 +4943,30 @@ bool ChainstateManager::LoadBlockIndex()
     return true;
 }
 
-bool Chainstate::LoadGenesisBlock()
+bool ChainstateManager::LoadGenesisBlock()
 {
     LOCK(cs_main);
 
-    const CChainParams& params{m_chainman.GetParams()};
+    const CBlock& genesis_block{GetParams().GenesisBlock()};
 
     // Check whether we're already initialized by checking for genesis in
-    // m_blockman.m_block_index. Note that we can't use m_chain here, since it is
+    // m_blockman.m_block_index. Note that we can't use a chainstate's m_chain here, since it is
     // set based on the coins db, not the block index db, which is the only
     // thing loaded at this point.
-    if (m_blockman.m_block_index.contains(params.GenesisBlock().GetHash()))
+    if (m_blockman.m_block_index.contains(genesis_block.GetHash())) {
         return true;
+    }
 
     try {
-        const CBlock& block = params.GenesisBlock();
-        FlatFilePos blockPos{m_blockman.WriteBlock(block, 0)};
+        FlatFilePos blockPos{m_blockman.WriteBlock(genesis_block, 0)};
         if (blockPos.IsNull()) {
-            LogError("%s: writing genesis block to disk failed\n", __func__);
+            LogError("Writing genesis block to disk failed");
             return false;
         }
-        CBlockIndex* pindex = m_blockman.AddToBlockIndex(block, m_chainman.m_best_header);
-        m_chainman.ReceivedBlockTransactions(block, pindex, blockPos);
+        CBlockIndex* pindex{m_blockman.AddToBlockIndex(genesis_block, m_best_header)};
+        ReceivedBlockTransactions(genesis_block, pindex, blockPos);
     } catch (const std::runtime_error& e) {
-        LogError("%s: failed to write genesis block: %s\n", __func__, e.what());
+        LogError("Failed to write genesis block: %s", e.what());
         return false;
     }
 
diff --git a/src/validation.h b/src/validation.h
index 4cb5dc63..2627cdce 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -809,8 +809,6 @@ public:
 
     /** Whether the chain state needs to be redownloaded due to lack of witness data */
     [[nodiscard]] bool NeedsRedownload() const EXCLUSIVE_LOCKS_REQUIRED(cs_main);
-    /** Ensures we have a genesis block in the block tree, possibly writing one to disk. */
-    bool LoadGenesisBlock();
 
     /** Add a block to the candidate set if it has as much work as the current tip. */
     void TryAddBlockIndexCandidate(CBlockIndex* pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
@@ -1085,6 +1083,9 @@ public:
     //! coins databases. This will be split somehow across chainstates.
     size_t m_total_coinsdb_cache{0};
 
+    /// Ensures a genesis block is in the block tree, possibly writing one to disk.
+    [[nodiscard]] bool LoadGenesisBlock();
+
     //! Instantiate a new chainstate.
     //!
     //! @param[in] mempool              The mempool to pass to the chainstate