Possible BUG : product(set[])*product(set[...])

[compsystems]

Hello, the product of an empty set is 1, so far everything is fine, but in the history, replace empty set, set[] with NULL and this generates an error when calling the entry and executing it again.

product( set[ ] ) * product( set[ a, b, c, a ] ) [enter] NULL*a*b*c -> 1*a*b*c // ok
[up][up][copy] product( NULL ) * product( set[ a, b, c, a ] ) // the null element in multiplication is 1
[enter]
"product(seq[]) Error: Bad Argument Value"

product( set[ ] ) * product(set[ 3, 3, 3, 1, 2 ]) [enter] 1*6 -> 6 // ok
[up][up][copy] [enter] "product(seq[]) Error: Bad Argument Value"