Type issues in Next 15/React 19 project #26
Description
Hey,
Seeing some type issues in my project:
given:
async function middleware(request: ChainNextRequest): Promise<ChainNextResponse> {
...
return NextResponse.next() // fails with below
}Type 'NextResponse<unknown>' is not assignable to type 'ChainNextResponse'.
Type 'NextResponse<unknown>' is not assignable to type 'NextResponse<unknown> & { [FinalSymbol]?: undefined; }'.
Property '[INTERNALS]' is missing in type 'import("/Users/rik/iso/Code/district/node_modules/.pnpm/next@15.1.7_@babel+core@7.24.6_@opentelemetry+api@1.9.0_babel-plugin-react-compiler@19.0.0-be_iwef3ria7cfvs2ks2iih7m4hgy/node_modules/next/dist/server/web/spec-extension/response").NextResponse<unknown>' but required in type 'import("/Users/rik/iso/Code/3p/nimpl-middleware-chain/node_modules/.pnpm/next@15.1.7_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/next/dist/server/web/spec-extension/response").NextResponse<unknown>'.ts(2322)
response.d.ts(11, 5): '[INTERNALS]' is declared here.
given:
async function middleware(request: NextRequest): Promise<NextResponse> { ... }
export const chainItem: ChainItem = [
middleware, // fails with below
{
include: /^\/m\//,
},
]Type '(request: NextRequest) => Promise<NextResponse<unknown>>' is not assignable to type 'Middleware'.
Types of parameters 'request' and 'req' are incompatible.
Property '[INTERNALS]' is missing in type 'ChainNextRequest' but required in type 'NextRequest'.ts(2322)
I think this is probably a Next 15/R19 issue but a cursory attempt to bump the Next version to 15 in this package locally didn't seem to work for some reason.
Seems to be fixable if I change my middleware request parameter to request: ChainNextRequest - this is fine but just making sure there's not an underlying incompatibility.
Thanks