calc(<LENGTH> - 0) should be simplified to <LENGTH>

[Jisu-Woniu]

I encountered this code snippet in my CSS:

.foo {
  margin: calc(100px - 0);
}

This should be simplified to:

.foo{margin:100px}

cssnano playground

But Lightning CSS outputs:

.foo{margin:calc(100px - 0)}

Lightning CSS playground

A input of 0px instead of 0 gives .foo{margin:100px} on both minifiers.

.foo {
  margin: calc(100px - 0px);
}

If this is an unsafe operation, let me know what the possible corner case is.