[BUG] `tile_min()` returns 0 when all tile elements are equal

### Bug Description

```python
@wp.kernel
def test_kernel(x: wp.array2d(dtype=float)):
    t = wp.tile_load(x, shape=(3, 3))
    min = wp.tile_min(t)
    print(min)

x = wp.ones((3,3), dtype=float)

wp.launch_tiled(test_kernel, dim=1, inputs=[x], block_dim=TILE_DIM)
```

prints
`[0] = tile(shape=(1), storage=register)`

### System Information

_No response_