vsprintf notice if a route function doesn't exists

vsprintf notice if a route function doesn't exists

When a routing error occurs because the target function doesn't exists, it returns a vsprintf() PHP notice instead of a routing error (Routing error: undefined function 'xxxxx').

Because the % can occurs in the error string, and isn't necessarily a placeholder % caracter, we should'nt use vsprintf() function in render()

This can be solved in render() function by replacing

else
{
   $content = vsprintf($content_or_func, $vars);
}

by:

else
{
    if(substr_count($text, '%') !== count($vars)) $content = $content_or_func;
    else $content = vsprintf($content_or_func, $vars);
}