Tern Link A7 dropping chain

My wife has a Tern Link A7, which I got her as a Christmas gift this las holiday. She hasn't really had much opportunity to ride it with some events that have been hitting us recently, but she has had it out 4-5 times total. Out of those 4-5 times, the chain dropped 3 times and was wedged between the crank away from the frame and the cover. So a few questions.

Is this something I can fix at home fairly easily? We have limited space being apartment dwellers, and my tools are limited. If I need more than a multitool, or what you would find in the most basic of toolboxes, I will not be able to do it.

Is there a reason this happens? Since I am not on the bike when it happens, and I have not been able to recreate the issue when I am riding it around the block, I cannot tell what the cause of the issue is.

Is this a common problem?

What can she do in the future to help prevent this?

I am likely going to make her take it back to the LBS we bought it from, and make her explain to the mechanic what is happening, so she can learn how to fix this on her own. I want her to be able to be able to fix it when I am not around. We have had the bike less than 4 months, so they should be willing to fix the issue complimentary since it is an issue that started right after purchase. But at the same time, I also want to have a little knowledge on how to fix it if necessary in the future.