Treat empty hidraw read as device removal (EOF)

When select() reports a hidraw fd as readable but os.read() returns
empty bytes, that's EOF per POSIX — the device has been removed.
Previously this was silently treated as no data, causing the listener
to loop indefinitely on a gone device instead of cleaning up.

lib/hidapi/udev_impl.py

@@ -403,6 +403,8 @@ def read(device_handle, bytes_count, timeout_ms=-1):
         data = os.read(device_handle, bytes_count)
         assert data is not None
         assert isinstance(data, bytes), (repr(data), type(data))
+        if not data:  # empty read when select() said readable means EOF (device removed)
+            raise OSError(errno.EIO, f"device disconnected on file descriptor {int(device_handle)}")
         return data
     else:
         return b""