@types/katex definitions are broken since v0.14 due to default export

[jameshfisher]

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• Check common issues.
• Check the bug is reproducible in the demo. If not, check KaTeX is up-to-date and installed correctly.
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Describe the bug:
@types/katex definitions use named exports, but katex v0.14+ switched to using a default export.

To Reproduce:
Steps to reproduce the behavior:

1. Install katex v0.14 or above
2. Install @types/katex
3. Try to use it, e.g. import { renderToString } from 'katex'
4. See runtime error: import is undefined

Expected behavior:
Types are consistent with implementation, i.e. should only allow import katex from 'katex' if KaTeX is only exporting a default value instead of named exports

Environment (please complete the following information):

• KaTeX Version: v0.14+

Additional context:
I have started a PR here

[edemaine]

It seems like we should support import {renderToString} from 'katex' in addition to the default export, even when using ESM. @ylemkimon is this hard to do?

[Stefaans]

@jamesfisher's pull request is failing CI tests. I am attempting another pull request:
DefinitelyTyped/DefinitelyTyped#59525

[jprinaldi]

It seems this was fixed at one point but now it's happening again. I tested with the latest versions of katex (0.16.10) and @types/katex (0.16.7).