I haven't seen any CP-2000 notices issued to decedents so I wouldn't worry about it too much. Just don't enter the post-death transactions in the first place. There may be an issue on a joint return, especially with CGD's that come late in December. The survivor should have sold the funds to avoid phantom income, but too late for that now.
Slaves to 1099's, Unite! You have nothing to lose but little pieces of paper.