RewriteEngine on
RewriteBase /
RewriteCond %{HTTP_HOST} ^www\.(.*) [NC]
RewriteRule ^/?(.*) %1/$1 [L,R=permanent]
RewriteCond %{THE_REQUEST} ^GET.*index\.php [NC]
RewriteRule (.*?)index\.php/*(.*) /$1$2 [R=301,L]

ErrorDocument 404 /error/404.php
ErrorDocument 403 /error/403.php
ErrorDocument 400 /error/400.php
ErrorDocument 500 /error/500.php