ValueError: non-hexadecimal number found in fromhex() arg at position 15

### Describe the bug

I've updated Python Can to 4.4.2 (not sure which version I was using before).
All of a sudden I'm getting a "ValueError" exception in bus.recv() every few minutes.

For now, I've handled the exception and proceed to wait for the next message.
it works, but now I miss an occasional packet from the CAN bus.

the exact message is:
/can/interfaces/slcan.py", line 218, in _recv_internal
ValueError: non-hexadecimal number found in fromhex() arg at position 15

the "position" always seems to be either 1 or 15 (havent seen any other numbers.

### To Reproduce

the code I use is simple:

CanMessage = bus.recv(35)

### Expected behavior

previous versions did not throw this error (ever)

### Additional context

OS and version: Ubuntu 24.04 LTS
Python version: 3.8.10
python-can version: 4.4.2
python-can interface/s (if applicable): SLCAN interface from TITAN (USB adapter)
https://www.titan.tw/product/usb-can-m/

Traceback and logs

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