test(llm_response_utils): cover the malformed payload guard where unit coverage runs

codecov/patch reported 0% of the diff hit: the new except-clause lines are in
llm_response_utils, but this test lived under tests/llm_translation, which the
unit coverage job does not run. Move it next to the other llm_response_utils
tests and add a positive case so the guard is proven not to swallow valid
payloads.

tests/test_litellm/litellm_core_utils/llm_response_utils/test_handle_invalid_parallel_tool_calls.py

@@ -0,0 +1,59 @@
+"""The hallucinated multi_tool_use.parallel expansion must not fail the response."""
+
+import json
+
+import pytest
+
+from litellm.litellm_core_utils.llm_response_utils.convert_dict_to_response import (
+    _handle_invalid_parallel_tool_calls,
+)
+from litellm.types.utils import ChatCompletionMessageToolCall, Function
+
+
+def _parallel_instance(arguments: str):
+    return [
+        ChatCompletionMessageToolCall(
+            id="call_1",
+            type="function",
+            function=Function(name="multi_tool_use.parallel", arguments=arguments),
+        )
+    ]
+
+
+@pytest.mark.parametrize(
+    "arguments",
+    [
+        '{"tool_uses": [{"recipient_name": "functions.get_weather"}]}',
+        '{"tool_uses": "nope"}',
+        '{"tool_uses": [42]}',
+        "{}",
+    ],
+)
+def test_malformed_tool_uses_returns_original_calls(arguments):
+    """A hallucinated payload we cannot expand must come back untouched."""
+    tool_calls = _parallel_instance(arguments)
+
+    result = _handle_invalid_parallel_tool_calls(tool_calls)
+
+    assert len(result) == 1
+    assert result[0].function.name == "multi_tool_use.parallel"
+    assert result[0].id == "call_1"
+    assert result[0].function.arguments == arguments
+
+
+def test_valid_parallel_payload_still_expands():
+    """The guard must not swallow well-formed payloads."""
+    tool_calls = _parallel_instance(
+        json.dumps(
+            {
+                "tool_uses": [
+                    {"recipient_name": "functions.get_weather", "parameters": {"city": "NYC"}},
+                    {"recipient_name": "functions.get_time", "parameters": {"tz": "EST"}},
+                ]
+            }
+        )
+    )
+
+    result = _handle_invalid_parallel_tool_calls(tool_calls)
+
+    assert [c.function.name for c in result] == ["get_weather", "get_time"]