code: public function handleHhvmError($code, $message, $file, $line, $context, $backtrace)
      {
          if ($this->handleError($code, $message, $file, $line)) {
              return true;
          }
          if (E_ERROR & $code) {
              $exception = new ErrorException($message, $code, $code, $file, $line);
              $ref = new \ReflectionProperty('\Exception', 'trace');
              $ref->setAccessible(true);
              $ref->setValue($exception, $backtrace);
              $this->_hhvmException = $exception;
          }
  
          return false;
      }
docs: Handles HHVM execution errors such as warnings and notices.
  
  This method is used as a HHVM error handler. It will store exception that will
  be used in fatal error handler
  
  @param int $code the level of the error raised.
  @param string $message the error message.
  @param string $file the filename that the error was raised in.
  @param int $line the line number the error was raised at.
  @param mixed $context
  @param mixed $backtrace trace of error
  @return bool whether the normal error handler continues.
  
  @throws ErrorException
  @since 2.0.6