Merge branch 'bugfix-8398' into 'release-5.2'

Bugfix 8398

See merge request !1073

modules/type/blocks/dap_chain_cs_blocks.c

@@ -850,6 +850,8 @@ static void s_callback_cs_blocks_purge(dap_chain_t *a_chain)
     }
     pthread_rwlock_unlock(&PVT(l_blocks)->rwlock);
     dap_chain_block_chunks_delete(PVT(l_blocks)->chunks);
+    PVT(l_blocks)->block_cache_last = NULL;
+    PVT(l_blocks)->block_cache_first = NULL;
     PVT(l_blocks)->chunks = dap_chain_block_chunks_create(l_blocks);
 }