fix(build): Refactor fallback values to be dummy overrides in createEdgeBundle (opennextjs#975)

* fix(build): Support function-valued overrides in override helper

* refactor

* changeset

* Revert "refactor"

This reverts commit a7ad1a2.

Author: sommeeeer

.changeset/lovely-goats-rest.md

@@ -0,0 +1,5 @@
+---
+"@opennextjs/aws": patch
+---
+
+fix(build): Refactor fallback values to be dummy overrides in createEdgeBundle

packages/open-next/src/build/edge/createEdgeBundle.ts

@@ -59,7 +59,8 @@ export async function buildEdgeBundle({
 }: BuildEdgeBundleOptions) {
   const isInCloudflare = await isEdgeRuntime(overrides);
   function override<T extends keyof Override>(target: T) {
-    return typeof overrides?.[target] === "string"
+    return typeof overrides?.[target] === "string" ||
+      typeof overrides?.[target] === "function"
       ? overrides[target]
       : undefined;
   }