Calling render without file or data produces a cryptic error message

[callumlocke]

On master, and doing sass.render({contents: input}, callback).

When input is an empty string, I get the error File context created without an input path.

[xzyfer]

Hi @callumlocke, node-sass@3.x (master) doesn't support contents as an option. You will need to use either file or data for file paths for file data respectively.

We should provide a more informative error message.

[callumlocke]

But contents works fine for me. (Just not with an empty string.)

[xzyfer]

Interesting... can you please supply an example of how you're using node-sass with contents?

[callumlocke]

No wait, maybe I am using data not contents. Not at a computer right now. I probably just entered the issue wrong. Sorry for confusion.

The point is, whatever property name I'm using, it works fine - except for when the value is an empty string, in which case I get the obscure error message.

[xzyfer]

Thanks for the clarification, I do think we need a better error message in this case.

[saper]

Empty braces cause this as well:

var sass = require('node-sass');

sass.render({
}, function(err, result) {
   if (err) {
        console.error(err);
   } else {
        console.log('successfully rendered');
   }
});

https://gist.github.com/95b3f79c73c0ab2a0a09

[callumlocke]

So there's two separate problems:

1. Cryptic error message if you fail to provide either file or data (i.e. if both are undefined).
2. If data is an empty string, node-sass behaves as if it's undefined, and errors out. An empty string is valid Sass so it should not error. Should I open this as a separate issue?

[saper]

No, no need to, thanks. This is actually the same issue.

[saper]

Should be fixed by #956. Now I think that the behaviour with render({}) is acceptable - we can complain either about data or file context; we don't know which one was really meant.

[callumlocke]

It still errors out for me if I try to render/import a file that happens to be empty.

[xzyfer]

@callumlocke the patch has not yet been merged. It'll be in the next release of node-sass.

[saper]

Would No input specified: provide options.data or options.file be a better error message?

I also wonder what we should do in case of async functions: show we call a callback and emulate a libsass error JSON object?

[saper]

#956 should be ready for testing.

[xzyfer]

Would No input specified: provide options.data or options.file be a better error message?

Yes. It's exponentially better.

I also wonder what we should do in case of async functions

You suggestion sounds legit.