Variable Visitor Wrong Transform

[vsn4ik]

Input:

import { transform } from 'lightningcss';

const res = transform({
  filename: 'test.css',
  minify: true,
  code: Buffer.from(`
    .foo {
      margin: var(--margin-y) 0; 
    }
  `),
  visitor: {
    Variable(variable) {
      return {
        raw: '30px'
      };
      
      // Same problem
      return {
        type: 'length',
        value: {
          unit: 'px',
          value: 30
        }
      };
    }
  }
});

console.log(res.code.toString());

Expected output:

.foo{margin:30px 0}

Actual output:

.foo{margin:30px0}

[Lalem001]

This issue was mentioned in a comment before, and needs more attention imo: #554 (comment)

Here is their playground link