If you pull up the skill tree for a duplicant who is out on a rocket mission, his status shows up as N/A (which makes a lot of sense and I assume works as intended).
However, if you try to click on a skill and assign it anyway, it seems to be a guaranteed crash.
Obviously, I was just curious and won't be doing it again, but thought ya'll should know.
Steps to Reproduce
1) Send out a rocket 2) Go to job/skill tree (default hotkey J) 3) Scroll to duplicant currently away on rocket 4) Click an unassigned skill
This issue has not been confirmed by a developer yet.