diff --git a/packages/next/src/client/components/react-dev-overlay/server/middleware.ts b/packages/next/src/client/components/react-dev-overlay/server/middleware.ts
index 451601e4978c8..aa081c29fb87d 100644
--- a/packages/next/src/client/components/react-dev-overlay/server/middleware.ts
+++ b/packages/next/src/client/components/react-dev-overlay/server/middleware.ts
@@ -111,7 +111,7 @@ export async function createOriginalStackFrame({
   rootDirectory: string
   frame: StackFrame
   errorMessage?: string
-}): Promise<OriginalStackFrameResponse | undefined> {
+}): Promise<OriginalStackFrameResponse | null> {
   const { lineNumber, column } = frame
   const moduleNotFound = findModuleNotFoundFromError(errorMessage)
   const result = await (async () => {
@@ -134,7 +134,7 @@ export async function createOriginalStackFrame({
   })()
 
   if (!result?.sourcePosition.source) {
-    return undefined
+    return null
   }
 
   const { sourcePosition, sourceContent } = result
diff --git a/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts b/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
index aa5d18e1b7373..d0fb87f772ad2 100644
--- a/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
+++ b/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
@@ -74,6 +74,7 @@ import {
   batchedTraceSource,
   createOriginalStackFrame as createOriginalTurboStackFrame,
 } from '../../../client/components/react-dev-overlay/server/middleware-turbopack'
+import type { OriginalStackFrameResponse } from '../../../client/components/react-dev-overlay/server/shared'
 import { devPageFiles } from '../../../build/webpack/plugins/next-types-plugin/shared'
 import type { LazyRenderServerInstance } from '../router-server'
 import { HMR_ACTIONS_SENT_TO_BROWSER } from '../../dev/hot-reloader-types'
@@ -955,7 +956,8 @@ async function startWatcher(opts: SetupOpts) {
             !file?.includes('<anonymous>')
         )
 
-        let originalFrame, isEdgeCompiler
+        let originalFrame: OriginalStackFrameResponse | null = null
+        let isEdgeCompiler = false
         const frameFile = frame?.file
         if (frame?.lineNumber && frameFile) {
           if (hotReloader.turbopackProject) {