That looks like an electrical connector lock clip. In other words it is what holds the wires in the connector and not let them back out.
I attached the testing for this code. I suspect something is left off so I can only suggest going back over what you took off. If you can't find it then run through the testing attached and you should find it.
Images (Click to make bigger)
Thursday, September 3rd, 2020 AT 6:25 PM