Improve documentation on is() and is.convert()() not beein equivalent

[Roang-zero1]

is and is.convert()() do not have the same behavior.

The function created through convert() do not have the same results as calling is() directly, even when using the same tests.

I've rewritten all tests from is() to convert()() at Roang-zero1/unist-util-is/tree/convert-test. Running these tests failes 14 tests (e.g. for invalid index).

Steps to reproduce

git clone https://github.com/Roang-zero1/unist-util-is.git
npm install
npm run test

Expected behaviour

From my understanding is() and convert()() should be equivalent.

Actual behaviour

is(node, null, -1) throws and error while

const testNull = convert(null)
testNull(node, -1)

returns undefined.

[wooorm]

Hmm, I don’t think they should be the same, otherwise, why use convert?
Convert is faster on valid input, precisely because it doesn’t test for invalid input, and that’s its use case

[wooorm]

Could be clearer in the docs!

[ChristianMurphy]

resolved in #13