Fix incorrect default export in TS declaration file

[andrewbranch]

The TS declaration file is loaded by TypeScript in the "typings" field of package.json. This field corresponds to the "main" field, which is set to ./dist/fuse.common.js, which does

module.exports = Fuse;

The correct TS representation of module.exports = Fuse is export = Fuse, not export default Fuse.

This is the root cause of many previous reports:

• Old namespace syntax for typescript definitions breaks when using ES Modules #679
• Usage in typescript without esModuleInterop #541
• Unhandled error TypeError: fuse_js_1.default is not a constructor #422

and was brought to my attention at microsoft/TypeScript#50058 (comment).

You can see the bug is also detected at https://arethetypeswrong.github.io/?p=fuse.js%406.6.2. Explainer: https://github.com/arethetypeswrong/arethetypeswrong.github.io/blob/main/docs/problems/FalseExportDefault.md.

Note also:

• This change allows users to import Fuse whether they have esModuleInterop set or not. While TS users should always set that option, when they have to in order to use a library, it always indicates that the library is misconfigured. It’s never a correct solution for a library to require TS users to set that option one way or another.
• esModuleInterop is irrelevant for users who are importing Fuse from a true ES module, as was attempted in Old namespace syntax for typescript definitions breaks when using ES Modules #679 and "moduleResolution": "NodeNext" throws ESM related errors microsoft/TypeScript#50058 (comment). Those users are completely unable to import Fuse without compiler errors without this PR, regardless of whether they set esModuleInterop.

I’ve thrown a lot of information at you, but I’m happy to answer any questions or concerns you may have!

[jstasiak]

I just tried this patch locally and it worked.

[andrewbranch]

This may be superseded by #727

[favna]

I have processed your review comment on #727 so I think you can close this one @andrewbranch

[andrewbranch]

Awesome!