Internal Server Error with Quick ban IP

this error

PHP Fatal error: Call to undefined function is_error () in /home/mysite/public_html/wp-content/plugins/better-wp-security/core/class-itsec-files.php on line 437

I shuts site
the last two days has happened several times
I also have the function of hide back end

now I need to connect to solve it via ftp eliminate the portion of the code

# BEGIN iThemes Security – Do not modify or remove this line
# IThemes Security Config Details: 2
# Quick ban IP. Will be updated on next formal rules save.
SetEnvIf REMOTE_ADDR “^ 196 \ .31 \ .40 \ .34 $” DenyAccess
SetEnvIf X-FORWARDED-FOR “^ 196 \ .31 \ .40 \ .34 $” DenyAccess
SetEnvIf X-CLUSTER-CLIENT-IP “^ 196 \ .31 \ .40 \ .34 $” DenyAccess
<IfModule mod_authz_core.c>
<RequireAll>
Require all granted
Require not env DenyAccess
Require not ip 196.31.40.34
</ RequireAll>
</ IfModule>
<IfModule! Mod_authz_core.c>
Order allow, deny
Deny from env = DenyAccess
Deny from 196.31.40.34
Allow from all
</ IfModule>
# END iThemes Security – Do not modify or remove this line

how to solve the problem?
my confguration WordPress 4.2.2
iThemes security Version 4.8.0

https://wordpress.org/plugins/better-wp-security/