SDSIO-Server - unclear error in playback mode when no datafile

[ReinhardKeil]

When there are no more datafiles, issue a clear error message such as:

Stream open failed: DataInput. File `DataInput.2.sds` does not exist. 
Closing USB Server...
Server stopped.

Currently the output is:

C:\w\SDS-Examples\Alif\AppKit\test>sdsio-server usb
Press Ctrl+C to exit.
Starting USB Server...
USB Server running.
USB device disconnected.
Waiting for SDSIO Client USB device...
USB Server running.
Ping received.
USB device disconnected.
Waiting for SDSIO Client USB device...
USB Server running.
Ping received.
Stream opened: DataInput (DataInput.0.sds).
Stream opened: DataOutput (DataOutput.2.sds).
...........
Stream closed: DataInput (DataInput.0.sds).
Stream closed: DataOutput (DataOutput.2.sds).
Stream opened: DataInput (DataInput.1.sds).
.
Stream opened: DataOutput (DataOutput.3.sds).
.......
Stream closed: DataInput (DataInput.1.sds).
Stream closed: DataOutput (DataOutput.3.sds).
Closing USB Server...
Server stopped.
Traceback (most recent call last):
  File "C:\Users\reikei01\AppData\Local\Arm\Packs\ARM\SDS\2.0.0\utilities\sdsio-server.py", line 1143, in <module>
    asyncio.run(main())
    ~~~~~~~~~~~^^^^^^^^
  File "C:\Python313\Lib\asyncio\runners.py", line 194, in run
    return runner.run(main)
           ~~~~~~~~~~^^^^^^
  File "C:\Python313\Lib\asyncio\runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "C:\Python313\Lib\asyncio\base_events.py", line 720, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "C:\Users\reikei01\AppData\Local\Arm\Packs\ARM\SDS\2.0.0\utilities\sdsio-server.py", line 1116, in main
    await srv.start()
  File "C:\Users\reikei01\AppData\Local\Arm\Packs\ARM\SDS\2.0.0\utilities\sdsio-server.py", line 928, in start
    await asyncio.gather(self._consumer(), self._out_sender())
  File "C:\Users\reikei01\AppData\Local\Arm\Packs\ARM\SDS\2.0.0\utilities\sdsio-server.py", line 838, in _consumer
    resp = self.mgr.execute_request(hdr + payload)
  File "C:\Users\reikei01\AppData\Local\Arm\Packs\ARM\SDS\2.0.0\utilities\sdsio-server.py", line 457, in execute_request
    if   cmd == 1: return self.__open(arg, data.decode('utf-8').rstrip('\0'))
                          ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\reikei01\AppData\Local\Arm\Packs\ARM\SDS\2.0.0\utilities\sdsio-server.py", line 364, in __open
    file_name = os.path.basename(self.opened_streams[sid][0].name)
                                 ~~~~~~~~~~~~~~~~~~~^^^^^
KeyError: 0