fix: deepMerge type issue for some variables

[sschw]

The current deepMerge function is mapping two objects of type T.

However the fetcherOptions of Context are general fetcherOptions while the variables and what is required by the fetch-function are request specific.

This causes type issues in the generated code. e.g. here in the example project:

  const { fetcherOptions } = useGithubContext();
  return reactQuery.useMutation<
    undefined,
    ActionsSetGithubActionsPermissionsOrganizationError,
    ActionsSetGithubActionsPermissionsOrganizationVariables
  >({
    mutationFn: (
      variables: ActionsSetGithubActionsPermissionsOrganizationVariables
    ) =>
      fetchActionsSetGithubActionsPermissionsOrganization(  // Expected type: ActionsSetGithubActionsPermissionsOrganizationVariables
        deepMerge(fetcherOptions, variables)                // Returned type: GithubContext["fetcherOptions"]
      ),
    ...options,
  });

Type definition:

export type ActionsSetGithubActionsPermissionsOrganizationVariables = {
  body: ActionsSetGithubActionsPermissionsOrganizationRequestBody;
  pathParams: ActionsSetGithubActionsPermissionsOrganizationPathParams;
} & GithubContext["fetcherOptions"];

According to the type definition, the variables are a type extending the fetcherOptions. This means, the deepMerge signature should be more like <T, U extends T>(target: T, source: U): U

I tweeked the existing function a bit to use above signature using a cast to the type we want to return. Also added || {} to prevent possible issues with nested calls when returnType might be undefined and returnType[key] call would therefore fail.
Function could also easily be changed to this signature <T, U>(target: T, source: U): T & U but left close to this use case.

I also updated the generated files in the example project.

[fabien0102]

I will close this one for now, this tweak is not working with the skipToken support #289

(I’m not happy about the as any in my implementation, so if you find something better please open another PR 🙏)

[sschw]

It would be a little change to make it compatible, as the generics can be <T, S> instead of <T, S extends T>. By just removing extends T from the definition, it would accept the skipToken, too.

However, I don't think, this is the right solution as I think, deepMerge in its current implementation should not allow accepting the skipToken as it would not return the skipToken.
When merging source into target, it would just return target if source is the skipToken. (See Object.assign({ header: {} }, Symbol("Test")) )

I'd instead suggest, to never call deepMerge with the skipToken and already do a check in the components functions.

See updated PR.