Description:
------------
When i call the __get or __set with an invalid member variable, the php interpreter is crash.
If i check the name with isset() then no crash!

PHP Version 5.2.4-2ubuntu5.3 (newest version in ubuntu)

Reproduce code:
---------------
class Test
{
  private $mVar = "var";

  public function __get( $name )
  {
     $name = "m" . $name;
     // if ( !isset( $this->$name ) ) return ""; //NO CRASH!!
     return $this->$name;
  }

  public function __set( $name, $value )
  {
    $name = "m" . $name;
     // if ( !isset( $this->$name ) ) return; //NO CRASH!!
    $this->$name = $value;
    echo( "Set: \$this->" . $name . " = " . $value );
  }
}

$t = new Test;
echo "Good: " . $t->Var;
echo "Bad: " . $t->Variable;

$t->Variable = "test";






Expected result:
----------------
Good: "var"
Bad: ""

Set: $this->Variable = "test"


Actual result:
--------------
exit signal Segmentation fault (11)