[JS API] .set("imports", []) overrides internally required imports option

[qnp]

Greetings,

Obsevations

As I coined in Vite project (vitejs/vite#2857), compiling stylus source with the following code will raise an error because .set completely overrides stylus option that are required for correct compilation, such as imports: ['node_modules/stylus/lib/functions/index.styl']:

const stylus = require('stylus')
const source = `$easing := cubic-bezier(0.4, 0.0, 0.2, 1)`
const options = { imports: ['path/to/my/variables.styl'] }

const ref = stylus(source)
// Here if you console.log(ref), you will see that this ref has
// an `import` option with the required internal file I mentioned

Object.keys(options).forEach((key) => ref.set(key, options[key]))
// Fails with "Cannot read property 'nodes' of undefined"
const result = ref.render() 

What is expected

ref.set(...) should merge options properly.

Workarounds are still possible (that is to say, pass options directly to const ref = stylus(source, options), but I had to mention this buggy behgaviour.

Best regards,

[zouhangwithsweet]

I have the same problem

[iChenLei]

Yes, this case is cause by design. tj design some built-in functions via functions/index.styl. So PRs welcome.

  options.imports = [join(__dirname, 'functions/index.styl')].concat(options.imports || []);

stylus/lib/renderer.js

Lines 162 to 164 in baba86d

	Renderer.prototype.set = function(key, val){
	this.options[key] = val;
	return this;