Allow display error on ... error & prevent token url error & Add link to thelia modules

This PR is a gift to @roadster31 , solving his #935 .
Now, thelia has error pages too. :kiss:

This PR solves #939 too.
This solves #938 too.

well, I was wrong. I thought ```(bool)"0"``` returned true but no. You're right, the integer cast isn't needed.