Better Typing support when suspense is enabled

Some restrictions can be applied to swr when suspense is enanbled:

• key can’t be falsy
• fetcher can’t be null
• data can’t be undefined

Note: this is tricky as TypeScript can’t handle inherited configs, and those can be dynamic in the runtime.

[MoSattler]

It is not, and that the reason why we have #1247 in the first place.

I believe OP and myself are asking for the typing to properly reflect the current implementation, not possible future changes that may or may not come.

In the current implementation it seems to be true that data cannot be undefined with suspense, and that is not correctly reflected in it’s typings, and that ought to be fixed.

[Svish]

My suggestion would be to just separate the two. Either a separate hook, or just a separate import like from swr/suspense or something like that.

That way you could simplify the regular hook by removing all suspense related stuff from there, and the suspense hook could be written with perfect types and no non-suspense related stuff.