diff --git a/src/logging/diagnostic-stability-bundle.test.ts b/src/logging/diagnostic-stability-bundle.test.ts
index 4b68c5f0eea..432443ae944 100644
--- a/src/logging/diagnostic-stability-bundle.test.ts
+++ b/src/logging/diagnostic-stability-bundle.test.ts
@@ -121,9 +121,11 @@ describe("diagnostic stability bundles", () => {
       },
     );
 
-    expect(result.status).toBe("written");
-    const bundle = readBundle(result.status === "written" ? result.path : "");
-    const raw = fs.readFileSync(result.status === "written" ? result.path : "", "utf8");
+    if (result.status !== "written") {
+      throw new Error(`expected written bundle, got ${result.status}`);
+    }
+    const bundle = readBundle(result.path);
+    const raw = fs.readFileSync(result.path, "utf8");
     expect(bundle).toMatchObject({
       reason: "gateway.restart_startup_failed",
       error: {
diff --git a/src/logging/diagnostic-support-export.ts b/src/logging/diagnostic-support-export.ts
index b401385bc7f..cb3a49ea61e 100644
--- a/src/logging/diagnostic-support-export.ts
+++ b/src/logging/diagnostic-support-export.ts
@@ -291,6 +291,13 @@ function isMissingPathError(error: unknown): boolean {
   return error.code === "ENOENT" || error.code === "ENOTDIR";
 }
 
+function configReadErrorMessage(error: unknown, stat?: fs.Stats): string | undefined {
+  if (!stat && isMissingPathError(error)) {
+    return undefined;
+  }
+  return error instanceof Error ? error.message : String(error);
+}
+
 function readConfigExport(options: {
   configPath: string;
   env: NodeJS.ProcessEnv;
@@ -316,13 +323,12 @@ function readConfigExport(options: {
       sanitized: sanitizeConfigDetails(parsed.parsed, options),
     };
   } catch (error) {
-    const errorMessage = error instanceof Error ? error.message : String(error);
     return {
       shape: configShapeReadFailure({
         configPath: redactedConfigPath,
         redaction: options,
         stat,
-        error: !stat && isMissingPathError(error) ? undefined : errorMessage,
+        error: configReadErrorMessage(error, stat),
       }),
     };
   }