Committing to database from code fails every 2nd try

I'm trying to purge an existing database with data, write mostly the same data there again, and then commit. However, there is something funny going on, since it works every 2nd time that I run the code. Every other time it fails. I finally caught a traceback that might be useful in tracking the cause of this down:

Traceback (most recent call last):
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\base.py", line 1256, in _execute_context
    self.dialect.do_executemany(
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\default.py", line 605, in do_executemany
    cursor.executemany(statement, parameters)
sqlite3.IntegrityError: NOT NULL constraint failed: entity_alternative.alternative_id

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\data\spi-entity\Spine-Toolbox\src\spinedb-api\spinedb_api\db_mapping_commit_mixin.py", line 59, in _do_add_items
    connection.execute(table.insert(), [x.resolve() for x in temp_id_items])
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\base.py", line 1011, in execute
    return meth(self, multiparams, params)
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\sql\elements.py", line 298, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\base.py", line 1124, in _execute_clauseelement
    ret = self._execute_context(
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\base.py", line 1316, in _execute_context
    self._handle_dbapi_exception(
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\base.py", line 1510, in _handle_dbapi_exception
    util.raise_(
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\util\compat.py", line 182, in raise_
    raise exception
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\base.py", line 1256, in _execute_context
    self.dialect.do_executemany(
  File "C:\Users\prokjt\AppData\Roaming\Python\Python39\site-packages\sqlalchemy\engine\default.py", line 605, in do_executemany
    cursor.executemany(statement, parameters)
sqlalchemy.exc.IntegrityError: (sqlite3.IntegrityError) NOT NULL constraint failed: entity_alternative.alternative_id
[SQL: INSERT INTO entity_alternative (id, entity_id, alternative_id, active, commit_id) VALUES (?, ?, ?, ?, ?)]
[parameters: ((1, 1, None, 1, 1576), (2, None, None, 1, 1576), (3, None, None, 1, 1576))]
(Background on this error at: http://sqlalche.me/e/13/gkpj)

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\data\Spine\ines-osemosys\ines-osemosys\osemosys_to_ines.py", line 447, in <module>
    main()
  File "C:\data\Spine\ines-osemosys\ines-osemosys\osemosys_to_ines.py", line 62, in main
    target_db = create_periods(source_db, target_db)
  File "C:\data\Spine\ines-osemosys\ines-osemosys\osemosys_to_ines.py", line 227, in create_periods
    target_db.commit_session("Added periods from YEARs to ines_db")
  File "C:\data\spi-entity\Spine-Toolbox\src\spinedb-api\spinedb_api\db_mapping.py", line 821, in commit_session
    self._do_add_items(connection, tablename, *to_add)
  File "C:\data\spi-entity\Spine-Toolbox\src\spinedb-api\spinedb_api\db_mapping_commit_mixin.py", line 67, in _do_add_items
    raise SpineDBAPIError(msg) from e
spinedb_api.exception.SpineDBAPIError: DBAPIError while inserting entity_alternative items: ('NOT NULL constraint failed: entity_alternative.alternative_id',)

Process finished with exit code 1

spine-tools / Spine-Database-API

Committing to database from code fails every 2nd try #440