I would go with "installation error". It is easy to make one there if you;re not careful or maybe not sure how it goes.
Not long after I bought my 93 I had a tire put on it and the kid who was given the task of installing it pulled the wheel off and the previous owners shop had put the hub on with using any locking washers. I was able to see somewhat from the waiting room, but was nigh on to making the window an entrance to the shop
Not sure how I could have done it wrong, I’ll try to replicate it tomorrow when I pick up the new manual swap parts. Thankfully O’Reillys has the part a few hours away and it will be ready for pickup in the morning. That gives me a spare set to put in the tool box along with the spare hub, bearings, and seals as well.