fix(memory): re-raise LLM extraction failures instead of returning [] (salvage of #5178) (#5878)

mem0/memory/main.py

@@ -22,6 +22,7 @@ from mem0.configs.prompts import (
     PROCEDURAL_MEMORY_SYSTEM_PROMPT,
     generate_additive_extraction_prompt,
 )
+from mem0.exceptions import LLMError
 from mem0.exceptions import ValidationError as Mem0ValidationError
 from mem0.memory.base import MemoryBase
 from mem0.memory.setup import mem0_dir, setup_config
@@ -912,8 +913,12 @@ class Memory(MemoryBase):
                 response_format={"type": "json_object"},
             )
         except Exception as e:
+            # Re-raise so callers can implement provider fallback / retry.
+            # The original silent ``return []`` made upstream callers unable to
+            # distinguish "LLM unavailable" (429/5xx/timeout) from "LLM
+            # extracted no facts" -- both surfaced as an empty list.
             logger.error(f"LLM extraction failed: {e}")
-            return []
+            raise LLMError(f"LLM extraction failed: {e}") from e
 
         # Parse response
         try:
@@ -2536,8 +2541,10 @@ class AsyncMemory(MemoryBase):
                 response_format={"type": "json_object"},
             )
         except Exception as e:
+            # Re-raise so callers can implement provider fallback / retry
+            # (see sync counterpart for rationale).
             logger.error(f"LLM extraction failed (async): {e}")
-            return []
+            raise LLMError(f"LLM extraction failed: {e}") from e
 
         # Parse response
         try: