More safety when errors occur early on, like when config sanity is being...

More safety when errors occur early on, like when config sanity is being checked. Prevents ugly warnings and a fatal error if dataroot isn't defined.

htdocs/auth/session.php

@@ -82,7 +82,7 @@ class Session {
     private function __construct() {
         // Resume an existing session if required
         if (isset($_COOKIE[session_name()])) {
-            session_start();
+            @session_start();
         }
     }
 

htdocs/lib/errors.php

@@ -117,8 +117,8 @@ function log_environ ($message, $escape=true, $backtrace=true) {
  * @access private
  */
 function log_message ($message, $loglevel, $escape, $backtrace, $file=null, $line=null, $trace=null) {
-    global $SESSION;
-    if (!$SESSION && function_exists('get_config')) {
+    global $SESSION, $CFG;
+    if (!$SESSION && function_exists('get_config') && $CFG) {
         require_once(get_config('docroot') . 'auth/lib.php');
         $SESSION = Session::singleton();
     }

htdocs/lib/mahara.php

@@ -498,7 +498,7 @@ function load_config() {
  */
 function get_config($key) {
     global $CFG;
-    if (array_key_exists($key,$CFG)) {
+    if (isset($CFG->$key)) {
         return $CFG->$key;
     }
     return null;