[BUG] RandomLeafFilter constructor will divide by zero during unit test.

### Environment
Debian Trixie

### Describe the bug
With FP exceptions enabled, the unit test will throw a FP exception for the RandomLeafFilter code, as it will divide by zero.

### To Reproduce
Enable FP exceptions (MR that adds toggle for this will follow.)

### Expected behavior
No FP exception thrown.

### Additional context
I have a fix, will create MR.
