Getting an error with my install

Just wondering if there is a fix for this?

Warning: array_key_exists() [function.array-key-exists]: The second argument should be either an array or an object in plugins/word-count-and-limit/wpwcl.php on line 339

Warning: Cannot modify header information – headers already sent by (output started at plugins/word-count-and-limit/wpwcl.php:339) in wp-includes/pluggable.php on line 1173

Thanks

https://www.ads-software.com/plugins/word-count-and-limit/