Fix the upgrade logic if the tags database was not created yet

src/tribler/core/upgrade/tests/test_upgrader.py

@@ -174,6 +174,26 @@ def test_upgrade_pony13to14(upgrader: TriblerUpgrader, state_dir, channels_dir,
         assert mds.get_value('db_version') == '14'
 
 
+def test_upgrade_pony13to14_no_tags(upgrader: TriblerUpgrader, state_dir, channels_dir, trustchain_keypair, mds_path):
+    tags_path = state_dir / 'sqlite/tags.db'
+
+    _copy(source_name='pony_v13.db', target=mds_path)
+
+    upgrader.upgrade_pony_db_13to14()  # No exception if the tags database file is missing before the upgrade
+    assert not tags_path.exists()  # Tags' database file is still missing after upgrade if it has not existed before
+
+    # TagsComponent specifies create_tables=True option when it creates TagDatabase.
+    # That means that the empty tags' database will be automatically created if it was not already present
+    tags = TagDatabase(str(tags_path), create_tables=True, check_tables=False)
+    mds = MetadataStore(mds_path, channels_dir, trustchain_keypair, check_tables=False)
+
+    with db_session:
+        # The end result is the same as in the previous test
+        assert upgrader.column_exists_in_table(mds._db, 'ChannelNode', 'tag_processor_version')
+        assert upgrader.column_exists_in_table(tags.instance, 'TorrentTagOp', 'auto_generated')
+        assert mds.get_value('db_version') == '14'
+
+
 def test_upgrade_pony12to13(upgrader, channels_dir, mds_path, trustchain_keypair):  # pylint: disable=W0621
     _copy('pony_v12.db', mds_path)
 

src/tribler/core/upgrade/upgrade.py

@@ -243,10 +243,11 @@ def add_column(db, table_name, column_name, column_type):
 
             self._logger.info(f'{version.current}->{version.next}')
 
-            add_column(db=mds._db, table_name='ChannelNode', column_name='tag_processor_version', column_type='INT')
-            add_column(db=tags.instance, table_name='TorrentTagOp', column_name='auto_generated', column_type='BOOLEAN')
+            if tags is not None:
+                add_column(db=tags.instance, table_name='TorrentTagOp', column_name='auto_generated', column_type='BOOLEAN')
+                tags.instance.commit()
 
-            tags.instance.commit()
+            add_column(db=mds._db, table_name='ChannelNode', column_name='tag_processor_version', column_type='INT')
             mds._db.commit()
             mds.set_value(key='db_version', value=version.next)