Fix order of optional argument reordering

[Qix-]

Q	A
Fixed Issues?	None
Patch: Bug Fix?	Yes.
Major: Breaking Change?	No.
Minor: New Feature?	No.
Tests Added + Pass?	We'll see (minor enough to warrant waiting for CI)
Documentation PR Link	N/A
Any Dependency Changes?	No.
License	MIT

Caught this looking into an unrelated issue with AST transformations. Previously, if the optional opts parameter wasn't passed, the intent was to move the function it held into the callback parameter and null out the opts param - but instead, it was nulling both.

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I'd actually suggest that callback is checked, too. Otherwise, erroneous downstream code could pass two functions (one for the callback and one, erroneously, for the options), thereby swallowing what should be a thrown exception about incorrect types.

I can add that logic in if wanted.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/8694/

[nicolo-ribaudo]

👍 for the additional validation. Can you also add a test which shows how the old behavior was wrong?

Also, this bug probably needs to be fixed also in the other files in that folder.

[loganfsmyth]

Woops, great catch. As @nicolo-ribaudo mentioned, we've got the same issue in

babel/packages/babel-core/src/transform.js

Line 21 in a811cf7

opts = undefined;

, so if you could fix those it'd be great.

[xtuc]

Good catch!

After a quick search I found another one:

babel/packages/babel-core/src/parse.js

Line 27 in 98ff2ce

opts = undefined;

[hzoo]

Added those ^, so we never added tests for async versions of those methods in #6780?

[hzoo]

Can merge now as well to fix the issue, but yeah we should figure out the tests too