fix(python): add missing space in the hybrid search error message (#4202)

`LanceHybridQueryBuilder._validate_query`'s ValueError concatenated two
adjacent string literals without a separator, rendering "...explicitly
for hybrid search.**But** not both.". Added the trailing space.
String-only change.

python/python/lancedb/query.py

@@ -2441,7 +2441,7 @@ class LanceHybridQueryBuilder(LanceQueryBuilder):
         if query is not None and (vector is not None or text is not None):
             raise ValueError(
                 "You can either provide a string query in search() method "
-                "or set `vector()` and `text()` explicitly for hybrid search."
+                "or set `vector()` and `text()` explicitly for hybrid search. "
                 "But not both."
             )
 

python/python/tests/test_hybrid_query.py

@@ -536,3 +536,15 @@ def test_normalize_scores():
             assert pc.equal(result, expected), (
                 f"Expected {expected} but got {result} for invert={invert}"
             )
+
+
+def test_hybrid_query_rejects_query_with_vector(sync_table: Table):
+    # Pins the full message: the space between "hybrid search." and "But" is
+    # load-bearing (see the _validate_query literal concatenation).
+    with pytest.raises(ValueError) as excinfo:
+        sync_table.search("dog", query_type="hybrid").vector([0.5, -0.5]).to_arrow()
+    assert str(excinfo.value) == (
+        "You can either provide a string query in search() method "
+        "or set `vector()` and `text()` explicitly for hybrid search. "
+        "But not both."
+    )