fix: ensure bedrock client handles stop sequences properly

Co-authored-by: Greyson LaLonde <greyson.r.lalonde@gmail.com>

lib/crewai/src/crewai/llms/providers/bedrock/completion.py

@@ -247,7 +247,7 @@ class BedrockCompletion(BaseLLM):
         self.top_p = top_p
         self.top_k = top_k
         self.stream = stream
-        self.stop_sequences = stop_sequences or []
+        self.stop_sequences = stop_sequences
 
         # Store advanced features (optional)
         self.guardrail_config = guardrail_config
@@ -267,7 +267,7 @@ class BedrockCompletion(BaseLLM):
     @property
     def stop(self) -> list[str]:
         """Get stop sequences sent to the API."""
-        return list(self.stop_sequences)
+        return [] if self.stop_sequences is None else list(self.stop_sequences)
 
     @stop.setter
     def stop(self, value: Sequence[str] | str | None) -> None: