Double check for when cols are nulls

Author: jeeminso

tests/bwc/test_upgrade.py

@@ -306,7 +306,7 @@ def assert_data_persistence(self,
                 cursor.execute(f'insert into versioned."{table}" (id, col_int) values (?, ?)', [str(uuid4()), 1])
 
             # to trigger `alter` stmt bug(https://github.com/crate/crate/pull/17178) that falsely updated the table's
-            # version created setting that resulted in oids replacing column names in resultsets
+            # version created setting that resulted in oids instead of column names in resultsets
             cursor.execute('ALTER TABLE doc.parted SET ("refresh_interval" = 900)')
 
             # older versions had a bug that caused this to fail
@@ -315,14 +315,18 @@ def assert_data_persistence(self,
             obj = {key: True}
             args = (str(uuid4()), version, obj)
             cursor.execute(
-                'INSERT INTO doc.parted (id, version, cols) values (?, ?, ?)',
+                'INSERT INTO doc.parted (id, version, cols) VALUES (?, ?, ?)',
                 args
             )
+            cursor.execute('REFRESH TABLE doc.parted')
             accumulated_dynamic_column_names.append(key)
-            cursor.execute('SELECT cols from doc.parted')
+            cursor.execute('SELECT cols FROM doc.parted')
             result = cursor.fetchall()
             for row in result:
-                if row[0] is not None:
+                if row[0] is None:
+                    cursor.execute('SELECT * FROM doc.parted where col is null')
+                    assert False, cursor.fetchall()
+                else:
                     for name in row[0].keys():
                         self.assertIn(name, accumulated_dynamic_column_names)
         self._process_on_stop()