[Model/Model] Remove: empty line.
[Model/OpUser] Fix: many
[OnePiece5] Change: StackError added static modifier.
[PDO/PDO5] Change: StackError changes to static operator
[merge] from origin develop
Merge branch 'develop' of https://github.com/TomoakiNagahara/op-core into develop
Merge branch 'develop' of https://github.com/TomoakiNagahara/op-core into develop
Merge branch 'develop' of https://github.com/TomoakiNagahara/op-core into develop