Thanks for the info Mcatrophy.
I neglected to provide an update, so here it is. The bike is now in good working order, but it took more work than expected. Not an issue if you've read this thread, but scary when you're not on the know.
It took 2 tries to reassemble the clutch correctly. Thanks to this thread for links and pictures
Then got the error code. That's when I panicked. Lost a night's sleep, but all was well after the clutch line bleed. Judging by the dark brown sludge that cam out, it was sorely needed.
I had found the clutch fluid reservoir behind the left panel, but had dismissed it because it was so small. Using the MightyVac didn't work for me because I couldn't get a good airtight suction. What did work well was using the ignition to let the internal pump build pressure. So the process was:
1. Turn ignition to ON
2. open bleed valve
3. close bleed valve
4. tuen ognotion OFF then ON again
5. aftern 3 times, refill reservoir
6. repeat many more times until you see clear fluid coming out.
The first test drive was a bit disappointing, but the smoothness quickly improved after going through all the grears a few times.
Very happy with the results, and it was definitely needed.
The only issue that did not get fixed is the cluck going from neutral into 1st gear. I don't know what to do about that.