Using currentcolor in color-mix() crashes (entered unreachable code)

[chris-morgan]

Using lightningcss@1.21.0 from npm.

$ node
Welcome to Node.js v20.2.0.
Type ".help" for more information.
> test=value=>(require("lightningcss")).transform({code:Buffer.from(`x{x:color-mix(in srgb,${value},blue)}`),minify:true}).code.toString()
[Function: test]

If you use two regular colours, it mixes them itself (✓):

> test`red`
'x{x:purple}'

If you use a variable, it skips it (✓):

> test`var(--x)`
'x{x:color-mix(in srgb,var(--x),blue)}'

But if you use currentcolor, it thinks it can do it because it’s a <color>, but it can’t actually since it’s resolved at runtime, and crashes (✘):

> test`currentcolor`
thread '<unnamed>' panicked at 'internal error: entered unreachable code', src/values/color.rs:2923:12
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Wouldn’t surprise me if currentcolor could cause other crashes too. I haven’t gone looking.