SeeedBus: Crash occsionally.

Bắt đầu trong can/interfaces/seeedstudio/seeedstudio.py quanh dòng 279, nơi _recv_internal đọc từ thiết bị nối tiếp, và tái hiện lỗi bằng một vòng lặp open nhanh cùng recv(0.0). Kiểm tra các bài kiểm thử interface SeeedStudio hiện có, nếu có, và làm cho đường nhận không chặn xử lý lần đọc rỗng như kết quả không có thông báo được mong đợi mà không phát sinh TypeError.

Describe the bug

python-can crashes rarely with the error:

    msg = self.bus.recv(0.0)
  File "/nix/store/0amvifzhc5sv3p1b29dzwxd53njs74z3-python3.13-python-can-4.6.1/lib/python3.13/site-packages/can/bus.py", line 121, in recv
    msg, already_filtered = self._recv_internal(timeout=time_left)
                            ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/nix/store/0amvifzhc5sv3p1b29dzwxd53njs74z3-python3.13-python-can-4.6.1/lib/python3.13/site-packages/can/interfaces/seeedstudio/seeedstudio.py", line 279, in _recv_internal
    end_packet = ord(self.ser.read())
TypeError: ord() expected a character, but string of length 0 found

To Reproduce

Use a while true loop to open the device quickly.
For my use-case, I needed to implement a flush_rx_buffer() function on user-level:
Please ignore my comments in the code, they may be outdated.

    def flush_rx_buffer(self):
        """Discarding the received buffer."""
        # As python-can does not implement any discarding of old messages, see:
        # https://github.com/hardbyte/python-can/issues/1721
        # The recv(0.0) is probably a non-blocking function, see:
        # https://python-can.readthedocs.io/en/3.3.2/interfaces/socketcan.html
        # That non-blocking function should return immediately.
        while True:
            msg = self.bus.recv(0.0)
            if msg is None:
                return

Expected behavior

Instead of a TypeError I expected to receive a None.

Additional context

OS and version: NixOS
Python version: 3.13
python-can version: 4.6.1
python-can interface/s (if applicable): seeedstudio

I'm using an asus nuc 15, so quite a fast CPU. I don't remember this error to appear on the slow raspberry pi pico.

def func():
    return "hello, world!"