        function onExit(code, signal) {
          removeListeners();
          let msg;
          if (typeof code === 'number')
            msg = `Received exit code ${code} while establishing SFTP session`;
          else if (signal !== undefined)
            msg = `Received signal ${signal} while establishing SFTP session`;
          else
            msg = 'Received unexpected SFTP session termination';
          const err = new Error(msg);
          err.code = code;
          err.signal = signal;
          cb(err);
        }
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.