There was no need to continue and let Unreal crash. Rather than speculating where the null pointer dereference came from (which would have been more work if you had more than one place that function is called from), your call stack was right there in the bottom right of your screen. The top line is where the crash occurred (the component’s AimAt); the line below that is that place that called the component’s AimAt, etc - hence the name call stack - a stack of all the function calls that got you to this point, going all the way back to main() in the executable.
Using this means you can check the state of your variables all the way along etc as well. Much less guess work that just looking at where the crash occurred only.
Cheers,
Alan.