fix(search): validate topic hierarchy input

backend/test_search_topic_taxonomy.py

@@ -66,6 +66,37 @@ class SearchTopicTaxonomyTest(unittest.TestCase):
             with self.assertRaisesRegex(RuntimeError, "normalized document 1"):
                 build(root)
 
+    def test_rebuild_rejects_normalized_document_without_classifier_list(self):
+        with tempfile.TemporaryDirectory() as temporary:
+            root = Path(temporary)
+            document = root / "documents/1"
+            document.mkdir(parents=True)
+            with closing(sqlite3.connect(root / "manifest.sqlite3")) as db:
+                db.execute("CREATE TABLE documents (code TEXT, state TEXT)")
+                db.execute("INSERT INTO documents VALUES ('1', 'success')")
+                db.commit()
+            (document / "document.json").write_text("{}", encoding="utf-8")
+
+            with self.assertRaisesRegex(RuntimeError, "general_classifiers list"):
+                build(root)
+
+    def test_rebuild_rejects_invalid_nested_classifier_branch(self):
+        with tempfile.TemporaryDirectory() as temporary:
+            root = Path(temporary)
+            document = root / "documents/1"
+            document.mkdir(parents=True)
+            with closing(sqlite3.connect(root / "manifest.sqlite3")) as db:
+                db.execute("CREATE TABLE documents (code TEXT, state TEXT)")
+                db.execute("INSERT INTO documents VALUES ('1', 'success')")
+                db.commit()
+            (document / "document.json").write_text(
+                json.dumps({"general_classifiers": [{"Name": {"Rus": "Корень"}, "GeneralClassifiers": "bad"}]}),
+                encoding="utf-8",
+            )
+
+            with self.assertRaisesRegex(RuntimeError, "non-list GeneralClassifiers branch"):
+                build(root)
+
 
 if __name__ == "__main__":
     unittest.main()