Add proper exit code

plugins/available/pretty-cat.plugin.bash

@@ -5,7 +5,7 @@ if [ -z $(which pygmentize) ]
 then
     echo "Pygments is required to use this pluging"
     echo "Install it by doing 'pip install Pygments' as the superuser"
-    exit                                                                                                 
+    exit 1
 fi
 
 # get the actual cat binary