When db server auto_increment_offset != 1, the default website browsing is error.

The message is:
```
QL ERROR [ mysqli ]

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 3 [1064]

SQL

SELECT * FROM phpbb_styles s WHERE s.style_id =

BACKTRACE

FILE: (not given by php)
LINE: (not given by php)
CALL: msg_handler()

FILE: [ROOT]/phpbb/db/driver/driver.php
LINE: 855
CALL: trigger_error()

FILE: [ROOT]/phpbb/db/driver/mysqli.php
LINE: 193
CALL: phpbb\db\driver\driver->sql_error()

FILE: [ROOT]/phpbb/db/driver/factory.php
LINE: 329
CALL: phpbb\db\driver\mysqli->sql_query()

FILE: [ROOT]/phpbb/user.php
LINE: 238
CALL: phpbb\db\driver\factory->sql_query()

FILE: [ROOT]/ucp.php
LINE: 36
CALL: phpbb\user->setup()
```

I found $this->data['user_style'] is not defined.