IsDeviceUsable in IOhidapi.cpp uses errno to detect if hid_write failed because of an unconnected Wiimote on a Dolphinbar (it expects errno == EPIPE in this case).
macOS’s implementation of hid_write detected this specific error (IOHIDDeviceSetReport returns kUSBHostReturnPipeStalled) but didn’t set errno so the check failed.
This add errno assignment to failure cases of macOS’s hid_write.