Proper error if the conf file is invalid instead of fatal error

Error:

An error occurred while parsing configuration JSON file (data/config.json.php): error code #4
➜ Syntax error
Please check your JSON syntax (without PHP comment tags) using a JSON lint tool such as jsonlint.com.

tests/config/ConfigJsonTest.php

@@ -40,7 +40,7 @@ class ConfigJsonTest extends \PHPUnit_Framework_TestCase
      * Read a non existent config file -> empty array.
      *
      * @expectedException \Exception
-     * @expectedExceptionMessage An error occurred while parsing JSON file: error code #4
+     * @expectedExceptionMessageRegExp  /An error occurred while parsing JSON configuration file \([\w\/\.]+\): error code #4/
      */
     public function testReadInvalidJson()
     {