fix: convert list/tuple to iterator before calling next() on tool_calls_validator

The current implementation assigns raw_tool_calls directly to
tool_calls_validator. If raw_tool_calls is a list or tuple (which are
iterable but not iterators), calling next() will raise a TypeError.

Explicitly convert lists/tuples using iter() to ensure
tool_calls_validator is always an actual iterator before next() is called.

Signed-off-by: Elizabeth Thomas <email2eliza@gmail.com>

Author: elizabetht

vllm/tokenizers/mistral.py

@@ -74,7 +74,10 @@ def maybe_serialize_tool_calls(request: "MistralChatCompletionRequest"):
                     f"'tool_calls' must be a list of tool call objects, "
                     f"got {type(raw_tool_calls).__name__}"
                 )
-            tool_calls_validator = raw_tool_calls
+            if isinstance(raw_tool_calls, (list, tuple)):
+                tool_calls_validator = iter(raw_tool_calls)
+            else:
+                tool_calls_validator = raw_tool_calls
             validated_tool_calls = []
             while True:
                 try: