[KVConnector] Enable get_block_ids_with_load_errors() in LMCache connector (#27978)

Signed-off-by: Zirui Liu <ziliu@ddn.com>
Signed-off-by: ziruiliu <ziliu@ddn.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Nicolò Lucchesi <nlucches@redhat.com>

vllm/distributed/kv_transfer/kv_connector/v1/lmcache_connector.py

@@ -136,6 +136,21 @@ class LMCacheConnectorV1(KVConnectorBase_V1):
         """
         return self._lmcache_engine.get_finished(finished_req_ids)
 
+    def get_block_ids_with_load_errors(self) -> set[int]:
+        """
+        Get the set of block IDs that failed to load.
+
+        Returns:
+            Set of block IDs that encountered load errors.
+            Empty set if no load errors occurred.
+        """
+        method = getattr(self._lmcache_engine, "get_block_ids_with_load_errors", None)
+        if callable(method):
+            return method()
+
+        # Fallback for older versions that don't support this method
+        return set()
+
     # ==============================
     # Scheduler-side methods
     # ==============================