With 21.2.1 I get:
(log #c(0 1) #c(0 -1))
Debugger received error of type: DIVISION-BY-ZERO #<a DIVISION-BY-ZERO 0x7f8925037640>
I also noticed that setting:
(si::trap-fpe t nil)
changes the result to:
(log #c(0 1) #c(0 -1))
#C(#<single-float quiet NaN> #<single-float quiet NaN>)
Paul