fix(lcm): Also added fix for BigUInt

Same as previous commit, but applies the change to BigUInt as well.

src/biguint.rs

@@ -1320,7 +1320,11 @@ impl Integer for BigUint {
     /// Calculates the Lowest Common Multiple (LCM) of the number and `other`.
     #[inline]
     fn lcm(&self, other: &BigUint) -> BigUint {
-        self / self.gcd(other) * other
+        if self.is_zero() && other.is_zero() {
+            Self::zero()
+        } else {
+            self / self.gcd(other) * other
+        }
     }
 
     /// Deprecated, use `is_multiple_of` instead.

tests/biguint.rs

@@ -1015,6 +1015,7 @@ fn test_lcm() {
         assert_eq!(big_a.lcm(&big_b), big_c);
     }
 
+    check(0, 0, 0);
     check(1, 0, 0);
     check(0, 1, 0);
     check(1, 1, 1);