500: Internal Server Error

Traceback

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/odoo/addons/base/models/ir_http.py", line 234, in _dispatch
    result = request.dispatch()
  File "/usr/local/lib/python3.8/dist-packages/odoo/http.py", line 809, in dispatch
    r = self._call_function(**self.params)
  File "/usr/local/lib/python3.8/dist-packages/odoo/http.py", line 350, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/odoo/http.py", line 339, in checked_call
    result = self.endpoint(*a, **kw)
  File "/usr/local/lib/python3.8/dist-packages/odoo/http.py", line 915, in __call__
    return self.method(*args, **kw)
  File "/usr/local/lib/python3.8/dist-packages/odoo/http.py", line 515, in response_wrap
    response = f(*args, **kw)
  File "/mnt/extra-addons/theme_afparis/controllers/website_blog.py", line 123, in news
    return self.af_blog_view(
  File "/mnt/extra-addons/theme_afparis/controllers/website_blog.py", line 53, in af_blog_view
    values = self._prepare_blog_values(
  File "/usr/local/lib/python3.8/dist-packages/odoo/addons/website_blog/controllers/main.py", line 95, in _prepare_blog_values
    offset = (page - 1) * self._blog_post_per_page
TypeError: unsupported operand type(s) for -: 'str' and 'int'