From cca6a7c989d4e951485c64766175abe30eb2ba9a Mon Sep 17 00:00:00 2001
From: Dan Tasse <105866+dantasse@users.noreply.github.com>
Date: Wed, 25 Mar 2026 21:49:29 -0400
Subject: [PATCH] fix: raise instead of return ValueError (#3189)

These couple of cases used to return ValueError; should raise it
instead.
---
 python/python/lancedb/query.py    |  4 ++--
 python/python/tests/test_query.py | 13 +++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/python/python/lancedb/query.py b/python/python/lancedb/query.py
index 66ff03a4a..8561f68de 100644
--- a/python/python/lancedb/query.py
+++ b/python/python/lancedb/query.py
@@ -70,7 +70,7 @@ def ensure_vector_query(
 ) -> Union[List[float], List[List[float]], pa.Array, List[pa.Array]]:
     if isinstance(val, list):
         if len(val) == 0:
-            return ValueError("Vector query must be a non-empty list")
+            raise ValueError("Vector query must be a non-empty list")
         sample = val[0]
     else:
         if isinstance(val, float):
@@ -83,7 +83,7 @@ def ensure_vector_query(
         return val
     if isinstance(sample, list):
         if len(sample) == 0:
-            return ValueError("Vector query must be a non-empty list")
+            raise ValueError("Vector query must be a non-empty list")
         if isinstance(sample[0], float):
             # val is list of list of floats
             return val
diff --git a/python/python/tests/test_query.py b/python/python/tests/test_query.py
index 2105a4dfa..a7153b010 100644
--- a/python/python/tests/test_query.py
+++ b/python/python/tests/test_query.py
@@ -30,6 +30,7 @@ from lancedb.query import (
     PhraseQuery,
     Query,
     FullTextSearchQuery,
+    ensure_vector_query,
 )
 from lancedb.rerankers.cross_encoder import CrossEncoderReranker
 from lancedb.table import AsyncTable, LanceTable
@@ -1501,6 +1502,18 @@ def test_search_empty_table(mem_db):
     assert results == []
 
 
+def test_ensure_vector_query_empty_list():
+    """Regression: ensure_vector_query used to return instead of raise ValueError."""
+    with pytest.raises(ValueError, match="non-empty"):
+        ensure_vector_query([])
+
+
+def test_ensure_vector_query_nested_empty_list():
+    """Regression: ensure_vector_query used to return instead of raise ValueError."""
+    with pytest.raises(ValueError, match="non-empty"):
+        ensure_vector_query([[]])
+
+
 def test_fast_search(tmp_path):
     db = lancedb.connect(tmp_path)