Oooh...
The first time I used it, everything was fine (although I couldn't "like" the forums/posts). So I disabled the extension and deleted the data via ACP (as I always do when I disable extensions).
I imagine that with this, phpBB will delete the Database tables and clean the board so that I can activate and use it again later.
Well...
Now I went to activate the extension again to test the permissions and the server returned an Error 500.
I tried to activate again and it generated this SQL error like the one in the image.
***********
EDIT:
I searched phpmyadmin, located the phpbbwn_ext table and deleted the extension related entry.
After I went back to my board and tried to activate, I got another Error 500.
And at the second try, again, the SQL error. Looking again at the db table, the entry is appearing there, but there is one more "notifications". I don't know the reason, but there seems to be an error with the extension when inserting the database.
Now I can no longer activate this extension.
EDIT 2: I've downloaded the fresh extension again. Deleted the old, cleared the cache and tried to activate. Error 500 and:
SQL ERROR [ mysqli ]
Duplicate entry 'naguissa/thanksforposts' for key 'ext_name' [1062]
SQL
INSERT INTO phpbbwn_ext (ext_name, ext_active, ext_state) VALUES ('naguissa/thanksforposts', 0, 's:13:\"notifications\";')
BACKTRACE
FILE: (not given by php)
LINE: (not given by php)
CALL: msg_handler()
FILE: [ROOT]/phpbb/db/driver/driver.php
LINE: 1031
CALL: trigger_error()
FILE: [ROOT]/phpbb/db/driver/mysqli.php
LINE: 202
CALL: phpbb\db\driver\driver->sql_error()
FILE: [ROOT]/phpbb/db/driver/factory.php
LINE: 353
CALL: phpbb\db\driver\mysqli->sql_query()
FILE: [ROOT]/phpbb/extension/manager.php
LINE: 179
CALL: phpbb\db\driver\factory->sql_query()
FILE: [ROOT]/phpbb/extension/manager.php
LINE: 241
CALL: phpbb\extension\manager->update_state()
FILE: [ROOT]/includes/acp/acp_extensions.php
LINE: 209
CALL: phpbb\extension\manager->enable_step()
FILE: [ROOT]/includes/functions_module.php
LINE: 676
CALL: acp_extensions->main()
FILE: [ROOT]/adm/index.php
LINE: 81
CALL: p_master->load_active()
Sad.