RequestInit - Type '"timeout"' is not assignable to type 'keyof RequestInit'

[agrofcsik]

@types/node-fetch version: v2.6.1
RequestInit is found in: node_modules/node-fetch/@types/index.d.ts

@types/make-fetch-happen: v9.0.2
node_modules/@types/make-fetch-happen/index.d.ts:25:9

Full Error:

node_modules/@types/make-fetch-happen/index.d.ts:25:9 - error TS2344: Type '"timeout" | "headers" | "agent" | "method" | "body" | "size" | "follow" | "redirect" | "compress"' does not satisfy the constraint 'keyof RequestInit'.
  Type '"timeout"' is not assignable to type 'keyof RequestInit'.

25         'method' | 'body' | 'redirect' | 'follow' | 'timeout' | 'compress' | 'size' | 'headers' | 'agent'

       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[nex3]

Dug into this a bit. Here are the relevant facts:

• The types in @types/node-fetch are for 2.6, for reasons detailed in node-fetch: restore types (for v2), update version, allow agent: false #58693.

• node-fetch 3.x now ships its own type declarations.

• Among other changes, node-fetch 3.x no longer includes a timeout option in RequestInit (as per source and docs).

• make-fetch-happen never actually depended on node-fetch.

• Despite this, @types/make-fetch-happen uses node-fetch's Request and RequestInit types.

• If you depend on @types/make-fetch-happen, the actual types it uses in practice will depend on which other packages you have installed. So if you (transitively) depend on node-fetch 3.x, it'll use the types declared there; if you don't, it'll use @types/node-fetch 2.6.

• But @types/make-fetch-happen is incompatible with node-fetch 3.x's types because it declares

  type NodeFetchOptions = Pick<
      RequestInit,
      'method' | 'body' | 'redirect' | 'follow' | 'timeout' | 'compress' | 'size' | 'headers' | 'agent'
  >;

  ...and if RequestInit doesn't have a 'timeout' field, this seems to mark 'timeout' as required in NodeFetchOptions.

This essentially creates a time bomb: anyone using @types/make-fetch-happen will be broken once any of their other dependencies starts using node-fetch 3.x.

I believe the root issue is that @types/make-fetch-happenshould never have used types from a package that themake-fetch-happenimplementation didn't depend on, and the fix would be removing that dependency edge and explicitly declaring the type forNodeFetchOptionsandRequest`.

The only workaround I can find so far is to either drop dependencies on make-fetch-happen or node-fetch 3.x.

cc @abernix who wrote the original #50339