fix types a bit

Author: ForsakenHarmony

packages/next/src/build/load-jsconfig.ts

@@ -58,7 +58,7 @@ export default async function loadJsConfig(
   )
 
   let implicitBaseurl
-  let jsConfig
+  let jsConfig: { compilerOptions: Record<string, any> } | undefined
   // jsconfig is a subset of tsconfig
   if (useTypeScript) {
     if (

packages/next/src/build/swc/index.ts

@@ -758,7 +758,7 @@ function bindingToApi(binding: any, _wasm: boolean) {
       ...options,
       nextConfig:
         options.nextConfig && (await serializeNextConfig(options.nextConfig)),
-      jsConfig: options.jsConfig && JSON.stringify(options.jsConfig ?? {}),
+      jsConfig: options.jsConfig && JSON.stringify(options.jsConfig),
       env: options.env && rustifyEnv(options.env),
       defineEnv: options.defineEnv && {
         client: rustifyEnv(options.defineEnv.client),

packages/next/src/server/lib/router-utils/setup-dev.ts

@@ -219,7 +219,7 @@ async function startWatcher(opts: SetupOpts) {
       projectPath: dir,
       rootPath: opts.nextConfig.experimental.outputFileTracingRoot || dir,
       nextConfig: opts.nextConfig,
-      jsConfig,
+      jsConfig: jsConfig ?? { compilerOptions: {} },
       watch: true,
       env: process.env as Record<string, string>,
       defineEnv: createDefineEnv({